Kai Parthy is a German engineer who creates odd printing filaments for 3D printers. His previous projects, LayWoo-d3 and Laybrick, are two non-warping plastics that offer wood and brick-like consistencies when extruded. Oddly, LayWoo-d3 actually smells like wood when printed.
Now he's created a bendable printing filament called BENDLAY that is 91% transparent and remains "bendable" after printing.
One of the problems with ABS plastic is that it can split and warp as it is formed and it isn't quite food safe. It is also very brittle and will "whiten" when bent, resulting in a messy final object. This filament is made of stretchy Butadiene, a form of synthetic rubber. It is foodsafe and can be used for clear bottles and containers and works well for flexible straps.
While ABS can be used to create flexible items like bracelets, this material will truly bend without breaking, allowing for hinges and other mechanical parts to be built into other, stiffer parts.
It costs $42 a roll, which is about right for a pound or so of 3mm filament, and comes on 750 gram rolls. It should work with almost any extruder-based device but, sadly, doesn't smell like fresh rubber.