Just a quick hobby + learning project. If people are interested I am happy to post more pics. PLA exterior + TPU seals + Nylon (COPA) bushings.
Everything is 3d printed except the hardware & motor. The hose adapters have 1/4 NPT ends on them. NPT has a tapered thread so I found that I could screw them in partway by hand then heat them up slightly with a soldering iron to soften the PLA then screw them in the rest of the way. Makes a nice watertight seal despite the roughness of the 3d printed threads. If they start leaking I can unscrew them (leaving behind threads perfectly molded to the fittings) then add some pip seal tape and put them back in.
What do you guys think?
EDIT: here’s a photo of the parts separate 
and a video: https://imgur.com/a/cd8co68
Thanks for sharing. My next TPU gasket seal iteration was likely a full flat gasket after fussing with more of a printed o-ring like bead with a flat flange and channels built into the mating parts.
As far as shaft seals, you’re in the “thar be dragons” region as far as I am concerned. Good luck!
Haha thank you! Yeah flat gasket is simpler & has worked so much better than past attempts at o rings and such. Definitely the way to go in my opinion. Just keep in mind when the grommet is compressed it grows horizontally slightly so you may need to inset the perimeter slightly. (You can see I had to do that with the interior section)