whit3rd fired this volley in news:c22c8298-6339-48d0-
:

A plunge router and a suitable circular jig would be my choice for
this.


And my choice would be a Forstner bit. I make holes in HDPE a few dozen
times a year. Twist drills won't do. Spade bits make for rough holes.
Forstners - fed at slow rpm and an adequately fast feed rate to prevent
softening of the work - make for a smooth hole in one cut.

LLoyd