A Trivet is used to protect your table from hot dishes. With a few handfuls of corks, some wood and a load of hot glue you can make your own trivet in next to no time.
Step 1: Acquire Corks
You'll need a load of corks of roughly the same size. I got a massive bag from Freecycle, but if you ask any restaurant they should be able to help you out.
For a drinks coaster sized mat you'll need 8 corks, for a 19cm x 19cm mat like the one I made you'll need 64 corks.