36" x 80" hollow core door with a sheet of HOMASOTE on top. Homasote is a sound deadening material that is quite dense and has great holding ability for the use of any type pins. 80" is fine for me because I don't know of many models these days that uses a one piece wing and you usually build one piece wings in two halves and then join them together. This can be done quite easily on a 80"
table.

Homasote is hard to find but I bought my last sheet at "Do-It-Best" hardware. It ain't cheep either. ( about $30 / sheet )