You don't have to take on any of the risk if anything breaks by forcing them to have renter's insurance. It's something that a lot of newer apartment buildings are doing these days.
You seem to be confused as to the purpose of renter's insurance. Renter's insurance does not cover the cost to repair broken appliances or problems with the apartment that reduce habitability. Not sure where you got that idea from. Renter's insurance covers the renter's property if something in the apartment damages it. For example, if there is a fire that damages your computer, renter's insurance will pay a replacement cost, but will not pay for the repair to the apartment. That is up to the homeowner's policy the landlord pays for.
Source: have rented solely in buildings requiring renter's insurance, and have never filed a claim for things breaking in the apartment. The landlord always fixes it.
You should definitely make sports compression gear with the material you have, I'm pretty sure people would easily pay 400-800 dollars per pair (myself included).
