My first real bench was a metal framed, pre-fabricated unit which used 1/4 " fiberboard for it's top and shelf. I had a 4x8 plywood 3/4" cut to replace the fiberboard. It still works out well and I have my Dillon and my RockChucker mounted there.
For my MEC 9000G shotshell reloader, I just made a frame and legs using nice straight 2x4 studs and then topped with a 3/4 plywood top.
Of the two, I like my all wood homebuilt the best. REgards, Mikey