yes you would have to have a surface under it. i have a workbench in which the top is made from plywood and i just lay the drywall on top of it. i know there are people who preach left and right about your surface must be absolutly level and perfact....trust me my workbench is far from level and building several models now useing nothing but drywall on top has netted me some very nice models. i think the only time the perfact streight and level bench comes into play is if you building musium quality other then that any problems that may incure from not haveing your workbench perfactly level are minumus and you wont even notice them from flying or looking. anyway thats enough rambing...basicly find a table, workbench, whatever to build on even if its just some one inch ply cut down and layed across saw horses and then put a hunk of drywall on top. works great and is cheap to replace when your a clutz like me and spill 1/2 oz ca all over it.....um not that i would have done anything like this...its just an example of what could happen....ya ya thats the story.