Lap desks do a good job of saving your lap from the toaster that is the bottom of your laptop, but they're often bulky for use on the go. Instructables user inspiredwood decided to solve that problem by creating one that collapses easily for travel purposes.
The table has two ends and a middle piece to support the laptop. You just insert the middle piece into the two sides to assemble it, and you've suddenly got a travel-friendly lap desk. When you need to take it with you, just disassemble all the pieces and they'll take up far less space.
You only need 12mm plywood to make the the pieces of this table. So long as you have some decent woodcutting skills (and the necessary tools), this should be a straightforward and simple project. If you want to give it a shot, check out the full post over at Instructables.
Travel PC table for commuters [Instructables]