The next best thing in the evolution of 3D printing: DLP/SLA resin systems such as Carbon 3D's CLIP system. In the near future we will finally be able to print non-porous, waterproof polymers that exhibit the same qualities as molded polyurethane.
Using a combination of Fusion 360 and Alias, we have been modeling concepts like this to send out to our rapid manufacturing bureaus. The thorn in our side is the fact that polyurethane rubber, in its common molded form, has not had the ability to be manufactured by rapid manufacturing until very recently.
