Making the best DIY tent footprint: Tyvek (tent groundsheet) - YouTube
Make a Tent Footprint : 6 Steps (with Pictures) - Instructables
Do you Need a Footprint for your Backpacking Tent? — Into the Backcountry
Amazon.com: Odoland Camping Tent Footprint and Tent Stakes Set, 83" x 83" Waterproof Tarp with Carry Bag for Under Tent, Ultralight Tent Footprint for Ground Camping Hiking : Sports & Outdoors