In article ,
Silvan wrote:

What do you think about 3/4" oak plywood as an insert? That's what I'm
planning to use. I have a few cutoffs with the short grain running across
the width. Not much good for anything else, but it's some nice plywood.
This seems like a good way to use it up and get rid of it.

3/4" will almost certainly be too thick and plywood doesn't plane down
real good.....unless you are planning our routing out the bottom for the
support thingies, which would seem to be a lot of pain.