NEMA 5-15R AC power entry connector panel mount into round hole instead of rectangular

[Steve]

Looking for a NEMA 5-15R AC power entry connector that will panel
mount into a round hole. All the ones I've found (Schurter 4300.0701
or Qualtek 738W-X2/03 for example) mount into a rectangular hole.
Easier to drill a round hole.

 

[Steve]

For >$15 vs <$1, I can cut a square hole.
That history update explains why I've had troyble finding the small
round 3 wire version of outlets used long ago in variacs to update
them with a ground. Thanks.