A remake of krunchy's power coupler. I enlarged the couper by 5% to get it to fit better. Added a hole in the middle to add extra perimeters for strength. Added a bevel to the outside to add strength to the shaft. Added support so it can be sliced with support turned off.
I suggest that this be printed with either ABS or PETG for the best results. Mine is working like a champ with PETG at 0.26 with 0.4 nozzle. I would suggest printing slightly hotter than normal so the layers bond really well.

Monoprice IIIP Mini Delta

No

No

.26

Yes

Use a strong plastic like PETG or ABS. Print it a little hot so the layers fuse completely. No special support needed as the support structures are built in. I suggest using 6 perimeters to strengthen the part.