Got the stirrer assembled (just with wire holding it together for now... need some tiny M2 bolts and nuts). Drive shaft coupled (with some plastic tubing). The chamber is assembled, with an extra layer of rubber at the top to make it high enough for the stirrer to fit (1/4" plexi is not 1/4" so the stirrer needs to be a bit less high on the next version). And the outlet fitting is ground down to 1/2" (1/2" hose couplings are not 1/2" so the holes need to be a bit bigger in the next version. Need a motor mount plate and then the mechanicals will be done, and we can move on to the electronics.

You can see the rubber wiper of the stirrer against the inside of the chamber. I'm not sure the rubber sheet I used will last... the material seems to be rubbing away like an eraser...