Flexible Filaments Only (TPU filament between 40 and 95A Duro)
I used Filatech's Flex 40:
https://www.prusa3d.com/product/filaflexible40-blue-filament-500g/
https://amzn.to/3fj7pHN Double Sided Tape
Recommend no brim but put some glue stick on the textured build plate as the flexible filament likes to warp and peel up at the corners.
The author hasn't provided the model origin yet.