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CC’s Booster Seat

Some projects we do are pretty straight forward- standers, tippy stools, easels etc. while others require a bit more problem solving and prototyping. One of our more recent projects fell into the latter category and became a really interesting mixed-material adaptation. We always enjoy these types of projects because it gives us a chance to think and work outside of our comfort zone. Often, these projects take quite a bit of time but with enough collaborative effort, the end result is well worth it!


“CC” is a 13 year old girl with cerebral palsy who needed a new seat for school. Her teachers and OT  wanted to get her out of her Rifton chair for certain activities and the seats in school did not promote good posture and provide enough support. The seat of the chair is slippery and has a pretty deep rearward slope which prompts you to slouch when sitting back. This of course is not a good position for anyone, let alone for a classroom setting.


Our solution was to create a removable booster seat that would provide a level seating surface and a more supportive back rest. In this case however, it was much easier said than done. The double curves of the chair proved to be quite a challenge to match however it was a crucial step in ensuring that the whole structure would be safe and sturdy. We experimented with heating ABS plastic to match the shape of the chair but then it became an issue of how we would build onto that. So, it was back to our good old friend, tri-wall cardboard. Using double layer sheets of the tri-wall, we constructed a few curved “ribs” that would fit the curves of the seat and attached them to a base that would become the new seating surface. This required a “bit” of trial and error–doing test fits, then sanding, fitting, then sanding and so on and so forth–seemingly infinitely. Eventually, we were able to match the seat pretty closely. The booster seat fit well enough that it didn’t really slide around at all on the seat so we were off to a great start!


Photo 1: Standard school chair used at CC's school.

Photo 2: Examples of curved “ribs” that would fit the curves of the seat to attach to a base that would become the new seating surface.


Next, we put together some footplates to compensate for the increased height of the seat. We made two footplates temporarily attached with velcro so that they could be removed as CC’s legs grow. We used plywood as a base and drilled out holes that would fit around the legs of the chair to keep the footplates from sliding around. Now that we had both components done, we went on our second fitting to try out our new design.

The seat worked very well and CC looked great in it but the therapists asked if we could add a tray so that she would have a surface to work on besides having to use a table like they initially thought. Normally, if we get a request from the beginning of a project, it’s easy to integrate certain features into the design. In this case, we designed the seat to be used with a table so it didn’t have the usual armrests and lateral supports that we build a tray onto. We always like a challenge and we always make sure that every child we build for gets the most appropriate adaptation we can provide–but admittedly, this one was going to be pretty tricky. With little time to lose, it was back to the drawing board and after several quick mock-ups and brainstorming sessions, we figured out a solution–it wasn’t going to be simple, but we would make it work.


A few sketches, a trip to the hardware store, and several hours later, we had our tray! We decided that the tray would need to have its own, foldable, legs to support it–which meant we would be mounting hardware. This led us to make the tray out of plywood rather than cardboard just to make the whole thing as sturdy as possible. The legs themselves were also made out of wood and the mechanism was a piece of 1″ aluminum tubing secured with rubber-coated conduit clamps that allowed just enough slip for the tube to rotate. In order to keep the legs a bit more secure in the folded position, we made a friction clamp out of ABS plastic.


Photo 1: Close up of mixed media stopper fixed to the back of the chair.

Photo 2: Close up of how the tray slides and locks into the mixed-media stopper.


To mount the tray, the booster seat itself had to be modified a bit. The tray had slots cut out that allowed the tray to be slipped onto the back of the seat but we needed to add stoppers to keep it level. Additionally, we added small cardboard/wood platforms for the legs to rest on. The final addition was a lock to keep the tray in place. This was a whole process in itself–figuring out the best way to do it–but in the end we added a wood section to one of the stoppers on the back of the seat and drilled a hole into it. This hole would line up with an eyelet bolt in the tray and then a pin could be placed through both, securing the tray in place. We also added a small length of bike brake cable to the pin to keep it attached to the tray. 


Now that we finally had all the components figured out, it was time to paint, add the straps and yoga mat for extra cushioning, and get CC’s new seat and tray delivered to her. We went with an all purple theme as it is CC’s favorite color (and she didn’t seem too fond of the primed white when we went to our first fitting).


CC was all smiles when we showed up with the finalized adaptation. All the trial and error, technical headaches, and time are well beyond worth it when you get a result like this.


Photo: CC in her new purple equipment



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