What:

A sealing insert that goes into the "Elegoo Centauri JesusFreak remix: Slotted Blank CC Riser for PTFE Tube" PTFE Slot

This will help seal the open space around the PTFE tube. It's a bit of a WIP. Could be adapted to other designs if you're handy in CAD. I have a few variations - one with the thin surface recessed and a "retraction friendly" one with the surface at the end of the insert. Also added some versions with thicker/wider flanges to help keep it in place. 

Printing:

Printed in TPU 95A, at the orientation it comes in as. In the .3mf file I added a priming cube of TPU to print first to ensure my dried TPU is coming out of PTFE tubes by the time I get to my real object I want to print. If you don't like it you can disable it. I used a 0.6 nozzle, 0.18 layer height, 2 walls, 15% infill.

Post Processing:

You may need to use a razor blade to re-slice/tear the slot for the ptfe tube. But it should be thin enough that it doesn't take a lot of force. The thin membrane is 0.65mm thick but I've added the .stp file so you can modify it as needed.