Humans are the only species that use toilet paper ... although some Vietnam veterans remember monkeys that wipe with their hands (and throw it at intruders). Design a sustainable alternative to TP that does not require pressurized water. Historical Examples: corn cobs, Sears Catalog, "soft rocks". (I'm winging this guys. Bear with...) What feedstocks are ubiquitous and cheap? What would it take to recycle junk mail into TP?