I like the original ptfe tube holder https://www.thingiverse.com/thing:3439584 and am using it inside my enclosure
However I wanted something to cover up the drilled holes on top where the ptfe tubes enter the enclosure
I sliced the bottom 2mm off of this and used it as a grommet for the top of the enclosure.
It has the added effect of acting as a drill guide so you can place the tube holder perfectly.
Just drill through the screw holes and now you will have holes to mount both the top and bottom pieces ensuring perfect alignment.