"Bob Mill" wrote in message
oups.com...
That's kinda was I was thinking, but here's a dumb question. Since
they old insert clipped into the table, but plywood insert isn't going
to be able to do that. How do you guys secure your homemade insert
into the opening?

Go to a hardware store or Lowe's and get a card of the little
adhesive-backed rubber "dots". These are the ones used to cushion cabinet
doors; or you stick them to the bottom of objects to protect table tops
(must be rubber or soft plastic). Stuck to the edge of the insert they
provide just enough friction to keep a fairly well-sized insert in place.