Fergmiester said:I just bought this stuff at the LHS last week and it looks like it definately will do the trick. It's called Foamtastic, comes in black, as well as other colours, it's a close foam rubber and comes in 9"x12" sheets and is about the same thickness as the distance between the top of code 100 rail and the top of the ties .
It's imported by Nicole, PO Box 846, Mt. Laurel, N.J. 08054
I suspect you would have better luck getting it at a craft store.