On Mon, 10 Dec 2012 20:46:11 -0500, tiredofspam nospam.nospam.com
There's nothing to making your own. Anyone who does woodworking should
be able to, and not is just a waste of money.
I cover mine with formica, to make it slide easier.

There's many types of suitable material for making inserts. I bought a
4x8 sheet of acrylic for an entertainment centre cabinet doors and
shelving. Had about 25% of it left when I was finished and have used
various cut off pieces of that for inserts.