There are a few drawbacks to recycled plastic. Although the ProtoCycler’s filament starts out with about the same strength as the standard stuff, it gets weaker with each reuse. Reprinting your model too many times might make it brittle and frail. Multicolored plastic also blends like paint. This isn’t a problem at first, but eventually your filament will end up brown. None of that is a big deal if you’re using the printer to rapidly prototype designs, when quantity matters more than quality. “Anyone can 3D-print something over and over again until they get it perfect,” Oosterman says.