Compression Bolt & Nut
UPDATE: Just added a solid version of the compression bolt.
This is part of a project I made for a friend that turned out quite nice even if I do say so myself. The bolt was originally a part from a gas dispersion unit I printed that required a tube to come out the top of the unit whilst applying pressure to the lid to squeeze it onto the gasket. I'm unsure of the pitch and thread size I used, I just remember making it large enough to get the compression the unit required. This may be able to be printed without support however I used support which ended up being annoying to remove and also required working the nut over the entire thread, essentially cutting a clean thread, once it was done it was a really good fit with heaps of holding pressure on the thread. I haven't yet needed to print this again so if someone is willing to try without support and inform me or the community I can edit this post to suit.
I haven't uploaded the original nut as it looks more like a lid of a canister and not really useful for anything other than what it was designed for. Instead I made a nut to suit this bolt that I'm sure can be used for something!