Wire Grommet

thingiverse

I used these to finish my speaker cable runs through the walls for my home theater. Instead of plain holes in the wall, I have nice grommets. To sit flush, simply lay a board over the grommet when inserted in a 1/2" hole and give it a tap. It should fit snugly up to the wall. Alternatively, take a hammer and gently dent the hole a few millimeters. Both methods work effectively. The hole is 1/4" and can accommodate most coax, ethernet or speaker wire, even jacketed ones. My 14mm in-wall rated speaker wire was incredibly tight, so your mileage may vary. Enjoy!