If you have a 3D printer at home, it almost certainly uses the FFF (Fused-Filament Fabrication) process. FFF 3D printing is relatively quick, very affordable, and provides decent quality. But, it also requires rolls of filament, and you can easily end up with dozens of rolls in different colors and materials. Daniel Harari’s Active Strain Relief device makes it possible to use all of those rolls without moving them from their rack.
Harari’s home 3D printing setup is a pretty common one. His 3D printer (two of them, actually) sits on a shelf, and his rolls of filament hang on a rod mounted above the shelf. That allows for easy access to the filament, but poses a problem if the roll is far away from the printer. In that situation, the filament has to reach across a large distance, which can cause the rolls to unspool and the filament to become strained.
The solution Harari came up with is a device that alleviates that strain by gently unspooling the filament next to the roll. A curved surface where the filament feeds in keeps it from developing sharp bends, and an extruder-like feed mechanism made from an inkjet printer’s rubber rollers pulls the filament off the roll as needed. It’s controlled by an Arduino and triggered by the force of the 3D printer’s extruder pulling on the filament, so it works automatically. All Harari has to do is position it in front of the spool being used, and it takes care of the rest!