I created this replacement pole adapter piece for a “MAINTAIN” brand pool vacuum head, because the other commonly available adapters wouldn't work with the 25mm space between the vertical supports that the bolt goes through. The adapter is meant for standard 1 ¼" (31.75mm) diameter pool poles. UPDATE: My original v1 design ended up breaking around the main bolt hole, so I've provide an newer “Pool vac head adapter v5” with a beefed-up section there, and a slicer file with higher density cubic infill.

I printed everything from black PETG, and I will probably coat everything with a UV protectant, but I may eventually try ASA if/when this part fails from being outside constantly. I printed the main piece upright, as shown, with an inner/outer brim, and I tried organic supports for the first time with Prusaslicer 2.6. They were used to support the main inside horizontal surface towards the top, and they worked really well!

I then printed the V-clip, which is actually made of two pieces that fit together. The additional smaller piece helps keep the clip ‘centered’ when the pole is not yet engaged with the adapter. The smaller piece just pushes and snaps into place:

I did it this way, because the two smaller pieces print a lot cleaner this way, with only the ‘buttons' sticking out needing some support. 

So far, this works great. Enjoy!