I guess this week was the intake valve.
For this to work with commonly-available o-rings, I had to resize the intake valve. That means the bellows must change size, too.
A lot of the look here is something I had to do to prevent needing supports. I think it’s neat that the look of the thing is informed by practical demands.
It’s designed currently to print with the flap side against the print sheet, so it’s nice and smooth. That may not be the important, though: I designed the valve so the butyl seal would get sucked into the tube a little bit, so smoothness may not matter. I’ll have to do some testing.