The Bugs entity posted thusly:

I make my own bases from polycarbonate scraps I get from the local
glass dealer. First mount the base to the router with careful layout of
the holes.

It's the 'careful layout of the holes' that's giving me problems. I
guess I could do it by using the existing router base as a template,
because it would be before cutting the central hole.

Tell me more about the polycarbonate (is that Lexan?) scraps. What
sort of thickness are they? Would they be suitable for a table base
(strong enough to not sag)?

Then install router bits of the right size to accomodate
whatever guide system you use and plunge the router through the base.
Makes a perfectly centered hole and is a Hell of a lot cheaper. I also
make custom bases for many different applications.
Bugs

Good idea, but how do I go about making the little ledge? My Freud
guide bushings go into a hole that is stepped, so that the face of the
bushing rides flush with the base.

Thanks,
Larry