Upgrade a used hollow core interior door into a decent lightweight table, with the help of a couple of pieces of construction lumber. The 1 x 4's around the outside give it a finished look and stiffen the table considerably, and with the help of a couple of crosspieces, give the legs something to be attached to. Assuming you have a free door, the table will cost you less than $5, and will recycle something that is otherwise likely to be dumped.
Step 1: Materials and tools
You'll need a used hollow core interior door - a smooth rather than an embossed one, of course!
One 10' length of 2 x 4 construction lumber, which you will rip into two 1 x 4's. Pick the straightest, cleanest piece you can find. If you don't have a bench saw, you'll need enough 1 x 4 to go around the table - approximately two 7' lengths and two 3' lengths (three 8' pieces is plenty).
One 8' length of 2 x 4 construction lumber, which you will rip into two 2 x 2's. Pick the straightest, cleanest piece you can find. If you don't have a bench saw, you'll need enough 2 x 2 to make the four legs and two crosspieces - approximately six 3' lengths (two 8' pieces is fine).
A bench (or table) saw is necessary to rip the 2 x 4's. A miter saw is handy to cut the wood to length. I used a brad nailer, wood glue, and a few deck screws to assemble the table. Wood filler, an orbital sander, and paint was used to finish the table, but all that is unnecessary if you're just going to use it as a utility table.