a round wall plate 50mm in diameter with a 25mm opening - Interlocking pieces break apart into two halves for reassembly around existing cables

thingiverse

This consists of two interlocking parts that split apart and can be reassembled around existing wires, resulting in a neater appearance. For a cleaner look, I omitted screw holes and secured mine with double-sided adhesive (sticky-tack putty is also an option and might be more paint/wallboard friendly). *** Update on tape vs sticky-tack: I recommend using sticky-tack putty because the double-sided adhesive tape I used lost its grip on the plastic after a day or so, while the sticky-tack remains in place. Additionally, the tape was difficult to remove from the wall. You might prefer to use the V2 file which provides for more space between the two parts, as the V0 version can be challenging to initially break apart after printing.