For children with certain conditions, hospitals will fit them with a resting hand splint. They must form to the child's hand very specifically for maximum comfort, must breath, and must be light.
Thermoplastic usually performs at least a few of these requirements well. However sheets of the plastic lack holes for ventilation. The other problem is, for Bangkok-based Queen Sirikit National Institute of Child Health (QSNICH), reliable thermoplastic suppliers offer sheets that are very expensive, perhaps 4,000-5,000 THB (115-140 USD) a piece and might make between 5-10 splints each.
We started by tracing a volunteer's hand and 2/3 of their forearm on a piece of paper. We scanned it and imported the image into SketchUp.
Then we 3D designed a basic, 2D template, including ventilation holes that also made the splint lighter and used less material. We printed it out, submerged it in 200 degree Celsius water, than applied it to a volunteer's arm and hand to form it. After 3 tries, it finally worked. The PLA plastic we 3D print with cools very quickly and is just warm to the touch by the time it makes first contact with one's arm, so if you make a mistake forming it, you simply resubmerge it for a few seconds until it becomes flexible, and try again.
The baseline price of the plastic used in the splint is only about 40 THB or about 1 USD. If QSNICH had their own in-hospital makerspace, they could print these out in approximately 3 hours each (or less since our volunteer was an adult, and children-sized splints would be smaller), keep small, medium, and large templates on hand, and make 10 times the number of splints for the same price as with their traditional thermoplastic solution.
|Paper mache prototypes developed by hospital staff as a low-cost alternative. Staff realized the limitations of this design, but used the models to give ProgressTH a clear idea of what the final prototype should look like.|
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