A lot of people will go with a hollow core door. And then you can build your own frame or put it on a old work bench, it's up to you. And some put ceiling tile on top of that so the pins will hold. I personally have a solid wood door ( I got it off a construction site that they where doing demo to for free ) and got (4) threaded flanges that I screwed to the underside and install (4) threaded pipes too for legs. I then have a 1/2 inch thick piece of sheet rock that I place on top of the entire door. If I ever have to replace the sheet rock it's only $5 for a sheet 4'X8'. That's gives you a starting point, and I'm sure you'll get plenty of ingenious ideas to follow you'll learn to be very resourceful. The best of luck building and enjoy the hobby. If you have other questions just shout them out there's always someone willing to help. I find this site very informative and a lot of knowledgeable people willing to lend a hand. Regards, Pat