I use 16 guage cold rolled steel and use magnets instead of pins. I was inspired by two things, the Great Planes magnetic buildboard, and more importantly, Paul Johnsons' website www.airfieldmodels.com.
It was not the least expensive option for building, but I plan on having my table for a long long time. There are photos of my first 2' x 4' steel board, and my new 4' x 8' build table in my photo gallery.

Scott