These are couplers for splicing US sizes of sump pump hoses together. In the hardware store they are less than $2 a piece, but i couldn't find any so had to model some up. They are designed to be a tight fit with my hoses so you may need to adjust.

No supports needed. They should load up in the correct orientation.

I suggest printing solid or nearly so with a lot of perimeters.

Keep your layer height to width ratio low to help with the overhangs on the barbs.

I printed with .8mm perimeters and .2 mm layer heights using a .4mm nozzle. Also had the seam set to random.

Most any common material should work. I used both abs and petg.