A few years back I went to a kink venue whee they had a thing called a Drildo. Prety much it is just a Vac-U-Lock on a shaft that connects in to a standard battery powered drill, had a dildo on the end and rotates. I really could not see the point of putting a round thing in a round hole and just making it rotate so I created "The Wobbler" the original was made from Aluminium and replaced one of the units at the club.
In addition to the STL's you will need :
1 X 608 Bearing (skateboard bearing) preferably sealed.
2 X M8 Button Head (low profile) hex bolts.
1 X M8 Lock Nut.
Be aware the thread between the Bearing Holder and the Back is LEFT HAND THREAD!
When assembling the thing there is a small 3 D Printed spacer that sits behind the bearing.
For a video to see how this thing works take a look at
Assembly is overall about 130mm long.
I printed the whole thing at 0.1 and a 4 layer wall thickness in ABS with a 15% infill.