Longshot replacement plunger head

Replacement plunger head for the longshot, to be used with 3.5mm o rings (I used 28mm ID). Ended up going with a o-ring seat that went from 28.4mm-29mm, found it gave a pretty good seal.

I made this to experiment with seal strength, I'm finding that mine is not outperforming the stock plunger head yet, but I wasn't fond of the stock shape anyway, so not a total loss.

I made this in 2 parts so that the bottom piece (defining the stretch of the o-ring) should be pretty easy to redesign and tweak as desired to match your o-rings, while the top piece, which has the potential to allow air through, needs to be sealed off. You can seal it off by printing it with higher quality, but in my case I'm pretty mediocre at printing so I filled it with ABS slurry and sanded it back. I've heard of people filling prints with CA glue, no clue if that's a good idea or no.

Also note that air can pass through the plunger via the centre screw hole, so I would advise you to fill it with hot glue or