A startup called HEYii claims they've developed infinitely reusable tracing paper. Called HEYtrace+, it's not actually paper at all, but a 0.5mm-thick silicone sheet with some type of proprietary coating; the company says it's nontoxic and allows you to erase the sheet using water (though they say 75% alcohol does a better job). You are somewhat limited to what you can draw with: The surface doesn't react well with pencils or oil-based markers. You can use alcohol-based markers like Copics, dry-erase markers, ballpoint pens, and water-based ink pens. The sheets come in A4 (8.3 x 11.7 inches) and A3 (11.7 x 16.5 inches). Oddly, both are priced the same: $35 each, with discounts available if you buy multiples ($99 gets you a 4-pack, for instance). The sheets come with a cleaning cloth and a piece of test material, if you want to try out a writing utensil to see if it will erase, without ruining the actual sheet.HEYtrace+ has been successfully Kickstarted, and there are nine days left in the campaign. They expect to start shipping them this April.