Calling it ‘plywood’ sounds better, but actually we used MDF (Medium Density Fiberboard), because it's cheaper and smoother. In any case, if you don't have a dining table big enough to comfortably seat a lot of your friends, plus fit a ton of tasty food on top, then don't worry, we have a solution.
Just grab a sheet of MDF from the big-box hardware store, strap it to the top of your car, and bring it home. Fellas, this is where we put in a pitch for every guy to have a car-top rack. It's not just good for hauling bikes.
Once you're home, throw that table-top on top of a couple sawhorses. Sawhorses are a great investment. If you don't already have some; you'll use them again and again. Screw the table down for added stability, and put some furniture pads under the sawhorses to protect your floor. Done.
Our costs for the table were:
Sawhorses: free (if you have some). But if you need to buy a set, they start around $25 on Amazon