BullDog Extruder mount with 1:4 speed reduction for 2.85 mm filament (for 3030 extrusions)

UPDATE: a more compact version is found [here](https://www.thingiverse.com/thing:2897762).

There are only a few good extruders for 2.85 filament found on this website but none of the ones I printed did work well enough for me. I decided to look what stuff I had laying around (as I did not have the time to wait for new parts) and designed a simple mount for a NEMA17 stepper and the aluminium BullDog Extruder (direct placment of the Bulldog extruder onto the NEMA17 did not work well and resulte