1st order of business is the rotary seal.
If you’ve got a rotary seal design you want to try or share, please don’t stop on my account.
If you don’t, you’ll get further down the road starting with a salvaged seal. It doesn’t need to come from a Rotovap, but that IS the easy place to look.
Stainless has enough advantages over glass that such a build would likely be a win.
You may or may not be better served by an FFE…
Depends on what you actually need.
Edit: @Rowan was playing with ferrofluid seals at one point, and might have a place you could go looking.