This is a snap on flange to terminate 20mm (nominal) flexible corrugated conduit flush with a surface- i.e. drywall/plasterboard. I made this so I can run the speaker wires to my rear home cinema speakers through the walls inside conduit. I have been searching for a way to terminate the conduit flush with the surface of the drywall, and behind the mounting plates for my speakers, so everything is hidden. I cant believe something like this doesn't exist! 

To mount flush, drill a 25mm hole in the surface, the body of the flange is just under 25mm OD. The max OD of the flange is 30mm. If you require a completely flush (or under the surface) finish, remove a 30mm ring to 1.5mm depth. 

The flange snaps on pretty tightly to 20mm flex conduit, so it's a semi-permanent fitment. A dab of CA glue will make it permanent.

This conduit is widely available- I got mine from Screwfix. It's 21.6mm OD and 16.5mm ID, but called “20mm”, so I guess that must be a nominal dimension. There are other sizes available, and dozens of manufacturers, so do a test print/fit beforehand! 

20mm conduit links: Screwfix Amazon

I printed in PLA, 0.3mm layer height with a 0.4mm nozzle on an i3 MK3S+. Its a quick print, and plenty strong. Full source files provided incase you want to tweak it or adjust dimensions for other sizes of conduit. 

I'll be installing these in a few weeks time so will return to update if there are any further redesigns required. 

It's always a pleasure to see people printing things I've designed, so please do share makes!