Are you sure you want to signup for Used postage stamps?
Check those used postage stamps you have!
On an ATC card (2 1/2 x 3 1/2) place a postage stamp on It using it as the topic of the ATC and add to it to create a scene of your choice. You may use cutouts for background, stamping for background or draw a background with the postage stamp as the subject.
For example: Stamp of a bird, then background it in a tree etc Stamp of an animal background of a forest or landscaping. Stamp of a building, landscape it.
In other words you are creating a scene around that used postage stamp creating a picture on that ATC. Any stamp goes, use your imagination. Check those used stamps you have from received mail.
One ATC to one swapper.