As demonstrated in a recent project, working on a door is a little easier when you have a few simple jigs, like this door buck:

It’s easy to make from scrap lumber and is small enough to conveniently tuck away until needed again.

Screws are driven through the plywood bottom into the blocks that hold the door. The feet are pieces of solid wood glued onto the plywood bottom:

Here’s a simple detail that shows the parts and dimensions. To view a larger version, suitable for printing, click the image: