by Ember » Sun Dec 23, 2012 7:54 pm
Corflute (ummm... that's a trade name, I'm sure it has others. The plastic corrugated cardboard used in the sign industry) and foamcore are nice easy options. Both are available in different thicknesses and easy to cut with a Stanley knife.
I used the corflute option on my track because I got 5mm thick for free. I packed it out to track height with cardboard and double-sided tape.
Embs