You can't trash old doors. No you can't do it even if they are crappy hollow core doors. Just paint them and make them portable work surfaces. One side has a matte clear coat the other awhite painted surface. Now I can expand my horizontal work surfaces and I've added hardware so that I can hang them from pulleys and drop them down for more drawing or display surfaces too.

It's like having a reversable jacket.

Flexibilty rocks.