TYVEK TARP SHELTER OR GROUNDSHEET - DIY - Buy TYVEK at your local retailer, i.e. Lowes, Home Depot, etc. Waterproof, yet breathable, spun DUPONT synthetic material. Comparatively inexpensive tarp material option; super strength to weight ratio, won't rip, won't fray. Mildew, mold, & microbe resistant properties. Folds into compact package, adds minimal weight to backpack load. (9 ft x 9 ft = +/- 9oz) - Process in washing machine to reduce noisy stiffness.