The theme for the August ATC swap in one of my groups is "Steampunk". Started with some background paper that reminded my of lab notes. One of my favorite tools, is a manila folder with an ATC sized piece cut out. I place this over the paper to decide which portion to use in my project. The lower piece is the one I choose.
Rubbed antique lined Distress ink over the paper, then used vintage photo Distress ink to create a stamped border around the ATC.