It lets you make 3D prints that slowly fade from one color to another along the Z-axis. [David Gozzard] wanted to do some printing with this effect, and learned how to make his own filament to do ...

Based on the work of [sekigon-gonnoc] and with help of [Thach], they’ve made their TinyUSB library support bitbanging of USB over PIO, and successfully ported their test jig firmware to it!