I asked a question the other day about inserts for router plates and the replys I received were very helpful, thanks. I thought the ones I located were a bit expensive for just a plastic ring, so I measured one and made my own using a circle cutting jig on my bandsaw. I used 1/8 inch acrylic that I purchased from a glass shop, it was very inexpensive, in fact if he had a piece in the scrap pile he would have given it to me, but he had to cut me a small piece.
It is sold as 1/8 inch, but it really is a bit smaller, perfect thickness. I cut a 4 inch circle then sanded it just a bit and used a hole saw to cut a 2 inch circle and I was in business. I was able to use my 1/2 inch round over bit and the dust collection seems to work better I think because the relief around the cutter is smaller.
Anyway, ir works great and I will be making more inserts as needed.