Triv-et N. : A metal stand with short feet, used under a hot dish on a table.
(Obviously these aren't made of metal, but they serve the same purpose.)

Here's a 30 minute project.

Literally. Thinking it up took longer than building it.

Pick a board from the scrap pile. I chose a 6" square maple board and a 6.5" square piece of cherry, both were about 7/8" thick. Put a dado blade in your table saw, set for a 1/4" wide cut, and a depth just a hair over half the thickness of the board. Set the fence so there is a 1/4" gap. Run the board, turn it 180 degrees and run it again. Flip the board over, and turn it 90degrees to the previous cuts and repeat the two cuts on this side. Move the fence half an inch and start over. Stop when the cuts meet at the middle of the board.

The end result is a mesh of cuts as you see in the photo's. You can adjust the width and number of cuts to make your own pattern.

One coat of Danish oil (Tried and True finish from Lee Valley Tools)

I'm treating this project as a sort of 3-dimensional sketch. I'm not sure at all if they'll last or if they'll warp, or perhaps crack due to all the cuts weakening the board. We'll see.

(NOTE: the cherry trivet, which is from a board that has been in my shop for 2-3 years, and should be dry and stable, almost immediately developed a small warp -- about 1-2mm -- So I would guess that all those dado's relieve some stresses/tension in the board. It'll be interesting to see if there are long term changes or not.)

Regardless, they're so easy to build, that even if they don't last it will be no big deal to make another one.

NOTE: Two and a half months later, the trivets are still in great shape. We use them almost daily with our meals.

A Further Note: Two years later... well I must caution you that while the trivets work great, they are on the delicate side. I've repaired a crack 2-3 times due to the trivet dropping to the floor. Let the builder beware.