Observation/Shadowing & Product Scale Testing

On February 5th, I was able to shadow PT on two physical therapy visits with Child A and Child B once again. Having a period of one month in between these two visits allowed me to see even further progress that they have made over a short period of time. These were my observations:

Child A – 15 months old; low muscle tone


PT spent the beginning of this physical therapy session working with Child A to stay in a hands and knees position. Instead of this being his usual way of moving around, he uses his head to scoot across the carpet while he lies on his back. In this position, he also arches his back and pushes off of the ground to gain movement. PT works with him on lifting upright on his arms and stomach so that it will transition into him moving around on his hands and knees as opposed to the position he currently prefers. She helps support him while she has him slowly move forward on his hands and knees.



PT places a mirror underneath Child A and holds him in the same hands and knees position that he was in before. Looking down at his reflection, Child A is interested enough to push upright in order to see his face, helping him stay held up on both of his outstretched arms for a longer period of time than usual. He enjoys looking at his own reflection but he needs to be a little further away from it to see it, so this helps keep him from laying down flat on top of it. In addition to the support that she is giving him with her own hands, PT has wrapped a “super wrap” around his hip and upper thigh area. It is a stretchy, bandage-like fabric wrap that holds his legs together and helps him stay a little more rigid.

Child B – 2 years (+ a few months) old; high muscle tone

2-5-15acopyPT started the therapy session by taking out a product called Theratogs and carefully putting it on Child B. Theratogs, designed by a physical therapist for children with neuromotor issues, is a garment that physically aids the child when it is worn. It comes in different parts so that it is easy to put on and remove, as well as so that it can be used on the areas of the body that require it most.


PT uses the medical device with Child B since it keeps him grounded, which allows him to be more patient during the physical therapy session. He is able to work for a longer period of time and it helps increase his stability throughout the session. It also helps him with his hip rotation alignment when he is put in to a kneeling position.

Product Scale Testing. 

In addition to just observing this session, I was also able to bring my first full-scale foam prototype of the first of the three final designs to test it for scale. The model was created the same way my previous scaled model was made; I designed the form on CAD, split it into stackable layers using Autodesk 123D Make, then used the CNC router to cut the shapes out of 1″ thick sheets of pink foam. I stacked the piecess together using spray adhesive then proceeded to carve and sand it into its final form.


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Child A, who is 28.5″ tall, is the perfect age and size to use as a scale reference for the model, so I brought it to the physical therapy session for him to interact with. Once I placed it next to him, I immediately saw that the model was a lot smaller than I had anticipated it to be. Although I was still happy with the form, I knew that there were a few modifications that were to come so that the scale could be perfected towards its user.

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The first modification to the full scale piece was that the thicker end, which is the end that the child’s head would be leaning on, needed to be widened. This would create a larger surface area that would be resting on the floor, increasing the design’s stability and making it sturdier and safer for a child to interact with. In addition, the entire piece need to be both lengthened and widened so that it could accommodate a child. Seeing it not only in full scale, but also next to a child in the age range of my user group, allowed me to gain a better sense of scale.

One great part of seeing Child A interact with the foam model was when he started crawling around it and playing with it. He was interested in its inviting, curvy form and continuously grabbed on to it. This made me see that although it is designed based on a specific developmental stage, its minimal form allows it to be used beyond that for different purposes during playtime.

Deciding on Final Forms

I began this stage of form sketching by making a list of the key developmental stages that my design will be focusing on. The benchmarks that made up this list were: lying down while lifting arms outright, ‘tummy time’, sitting upright, balancing, crawling, creeping, and moving objects. The three pieces that compile my overall design will each be designed around a couple of these stages. However, they will have additional uses as well so that they will not have a limited usage time and as the child develops he/she will use them in different ways through exploration.

In addition, each one of the three pieces advance in movement from one to the next. As the child progresses physically, the pieces somewhat follow along in a sense as their own movement is increased. It is a subtle way for the design to grow alongside the child who is using them as they reach their milestones.

Going through the stages of development I am focusing on, I made a list of necessary and optional components that each position would require for support. For lying down while working on arm strength, the child will need head support and upper back support. Support that is optional would be underneath the entire body, underneath the arms, and slightly underneath the knees. For ‘tummy-time’, necessary support would be underneath the child’s chest as well as underneath the arms. Support that might be helpful but is not necessarily required would include a front curve to hang the arms over, underneath the entire body, as well as around the body. For sitting upright, back support and support behind the neck area would be required. Optional support includes under the leg support and surrounding support. Based on these components, I sketched basic forms that would accomplish all of the above in three separate pieces. These sketches, along with all of the research that I have done up until this point, have led to my three final form choices:


(This diagram shows basic sketches for all three of the following design explanations, starting from the left side.)

Three Final Form Design Explanations:

1. First Design. 

This first form focuses on helping the child with arm lifting and ‘tummy time,’ both of which are stages in which the child has limited mobility in most of their body. These stages are an important area of focus since they are the foundation of all other developmental stages. The minimal form, meant to be used on both sides, has curves designed for specific positions. The specific placement of varying textures will initiate further movement in the child’s arms and legs. Ideally, the finished product would be made of a soft yet rigid material that will increase the child’s comfort by giving in slightly to their body weight while still supporting them off the floor.

2. Second Design.

This second design focuses on the developmental stages of sitting upright, balancing and learning to climb on and off objects. All of these involve the child learning to keep their upper body upright as well as maintaining that upright position stably for a period of time. The form has specific curves and thicknesses that are designed to be multi-purpose in function. Placed in one direction, it can be used to improve the child’s sitting position. A 90-degree back rest initiates the child to sit with proper posture comfortably. Textures are placed in specific areas for sensory stimulation and motivation for reaching outward.

When it is flipped upright, the design is used as a rocker. It is designed to be low enough for the child to place their feet on the floor while sitting on it and a bumpy texture serves as stoppers on the underside to prevent the piece from rocking too much. This rocking motion will increase the child’s balancing ability through play, further advancing on their physical advancement as well as their motor skills. Another possible addition is that the form will be filled with sand. This could serve as a base support that will shift where it is needed when the piece is moved from one position to the next.

3. Third Design.

This last design focuses on more advanced stages of mobility, including crawling, creeping and moving objects. These are the stages in which the child has gained enough mobility to begin moving about their surrounding environment. They are also the stages when the child is playing more independently than before, allowing the parent to observe their child’s progress as opposed to having the child rely on them for help. This piece has no set position; it is meant to rotate in order to move with the child.

The child is able to crawl through and feel the different textures lining the interior surface of the form. They can push the lightweight piece in order to work on arm strengthening as well as to chase after it, increasing their ability to both crawl and creep. Keeping the child’s interest with a unique form that is able to move will help them advance on these movements without having to think about what they are doing. They can also lie inside and reach around to grasp different areas and feel through the gaps, which will help increase their fine motor skills.

All three of these pieces are meant to be used both individually and as a unit. They were designed with specific functions in mind, yet their ambiguous forms allow their usages to extend further than those intended purposes, giving them a longer lifespan than other similar products currently on the market.

Testing Size: Making a Half-Scale MDF Mock Up

At this point, I decided to push forward with my latest 3D print advancement in order to scale it up. The 3D print is only about 5 inches long, which is helpful in identifying the form but not so much the function. I wanted to see how stable the piece would be in a larger scale, as well as to see exactly how big the final product should be. This latest print has a simple curved form that varies in thickness from one end to the other. It is able to be placed in four different positions while staying upright and each position is useful for different activities. The main position it stays in allows it to subtly rock and spin since the widened base has a slight curve, which is enough to initiate movement while keeping safety in mind:


I proceeded to take the CAD file for the model into a program called 123D Make, which allows you to turn your 3D model into a two dimensional build plan. The program takes the three dimensional form you have created and slices it into layers upon your direction. I was able to choose the direction and width of the slices it would be made up of based on the material it was cut from. In addition, I hollowed out the inside so that I could fill the end piece with sand in order to test the shift in weight when placed in different positions.

In order to choose the size of the larger scale model, I researched the average measurements of a child in the age range of my user group. It turned out that the average height is about 31″, so I decided that the overall length of my first test piece would be 36″. I figured it should be a little bit larger than the child so that they can sit on it and interact with it without it being too overwhelming to them. Since the CNC has limitations due to the material choice, I had to create an 18″ half scale model. It would still allow me to test the function on a larger scale than the 3D print and pave the way for future iterations.

I chose MDF as the material to use for the model because it comes in large sheets that are easy to sand once the pieces have been assembled. After setting up the material onto the CNC, it was time to start cutting out the pieces. 123D Make works with the CNC router so the new file had to be transferred to the machine, allowing it to then follow the line paths that were programmed.

After all the pieces were cut out of the MDF sheets, the assembly process began.

I had to remove all of the unnecessary material from the interior and exterior of each part. I numbered them in size order to keep track of the way in which they would be glued together.

I was left with only the pieces required for my model and I continued to work on each one by hand. I used a hand file to clean up all of the edges to give the overall piece a smoother finish at this stage. Although somewhat time-consuming, it saved me time later on in the construction process.

During the sanding process, my thesis advisor, Professor Stan Rickel, and I discussed the best way of going about assembling the pieces. It required multiple wooden dowels to be placed through pre-drilled holes in order to keep the pieces from shifting during the gluing process.

I proceeded to widen the pre-drilled holes after all of the sanding was complete so that there would be room to apply wood glue around the dowels to keep them securely in place without falling out. I then split the parts into two piles and glued the pieces into two separate halves. This would enable me to fill the piece with sand before gluing the two halves together. I hoped that the sand would create the weight-shifting ability I wanted in the final design, however, the MDF was too heavy a material for it to really make much of a difference. I would like to test it out with a foam model, which would allow the sand to make more of a difference due to its lighter quality.

Both halves were carefully glued and clamped to ensure a close fit. I left them to dry overnight, added the sand to one half in the morning and then glued the whole piece together. I gave the piece more time to dry this time since the next step would entitle sanding down the entire surface to shape and smooth the exterior.

I clamped the entire piece securely onto a table in the industrial design studio’s sanding room. Using a hand grinder, I went over each section of the piece so that there would be a continuous surface over all of the glued pieces. I had to continuously rotate the model and re-clamp it to ensure an even surface all around. In the end, the room was completely covered in MDF dust from the excess material removed and my piece had been sanded down to the necessary form.

When the time came to finish the surface of the piece by removing all of the sanding marks, Stan happened to be in the industrial design studio with furniture designer Wendell Castle. Wendell uses a wood stacking technique similar to this in many of his pieces, so he took the time to give me advice on how to complete mine more efficiently. I carefully removed the markings from the hand grinder so that the curves would have a better flow and a smoother surface.

After the piece was completed, I began to take notes of its qualities. A thinner wall would be better, allowing there to be more hollow space inside for the sand to partially fill and allow a more noticeable shift in weight. When it came to size, this definitely help me see a more realistic scale of the final design. Even though it was just a half scale representation of what the final form would be, it allowed me to see that at full scale the piece would be too large. Instead of 36″ long, it would be sufficient for the piece to be minimized to approximately 25″ long. A smaller size will allow it to be used properly without being excessively large. In addition, no extra material will be wasted and the proportion to the child will be more in scale.

Less Design is More Design

Meeting with my Advisor: PT

I brought my current 3D prints to show PT in order to look at them with her. Instead of looking at them from the perspective of a designer, it really helped to hear from a physical therapist how she thought the forms might be able to help children with abnormal muscle tone.

In the case of adding a slightly curved area in which the child might be able to sit on, PT suggested that I focus on creating a curve that will subtly add leg support when the child is sitting. By creating a downward slope in the angle of the sitting curve, it increases the amount of flexion in the hip, reducing the potential for the child to slide out of the chair. This is a safety concern since they sometimes lack the control required to hold their body upright on their own. The quick diagram below might make it easier to understand the difference between the two positions:


However, once the child is able to sit in that on their own, they will not necessarily need that section of the design anymore because they will be able to move. This seating position restricts other movements so if it used in the final design, adjustments will be required. The downward angled slope in the seat base might not need to be as drastic nor would the seating curve need to come up very high off the ground. A lower seating area would allow the child to keep their feet touching the floor underneath. This design aspect will need to be used for other activities as well since limiting parts of the form to such a specific function might make using the design at home harder for both the parent and child.

PT told me that babies usually curl up their legs instead of stretching them outright. In order to allow them to sit with their legs upward, the sitting curve must be wide enough to give them the knee room required to do so. If a physical therapist is working with the child in a home environment, the parent might remove a seat cushion from their couch, sit the child in the corner, and put a cushion in front of them between their legs in order to add something to support them from falling forward.

This last bit of information gave me the idea to create a sitting curve wide enough for the child to sit on with their legs comfortably positioned outward. There would be a structure in the middle sticking upright for the child to use to lean on for added support, such as this diagram indicates:

SittingSupportAfter explaining this new idea to PT, she gave me some incredibly useful advice in which she started off by saying that “at the end of the day, parents should be the toy of the child.” By not adding support pieces, it leaves more room for the parent to help the child. The parent is able to come in and give both mental and physical support to their child during play as opposed to the design doing all of the work itself. It enhances their interaction instead of assuming that the child is able to use the toy on their own. As time passes and the child becomes more independent, the parent being there is no longer a ‘need’ as much as a ‘want’. The parent is able to use the design with their child, thus increasing their quality time together. In the words of PT, “the time you give to your child gives back way beyond your imagination as they get older.”

Less design is more design. Essentially, leaving more room for the parent to help the child allows for an overall greater parent/child interaction during playtime.