The coil frame for the antenna tuner in my earlier post to Brian is made of a Pioneer Plastics Corian clone. It was assembled with drilled and tapped machine screws. I don't recall what I used but something common like an 8/32 would be a safe bet. Have you considered making your fiddles out of Corian? If you can find a local shop that will sell you the correct colored adhesive that might be an option. You'll just need a bunch of clamps. The stuff is easy to shape and trim with carbide router bits.