Perhaps do something similar to what armory does although make it on the market?
Mechanics: Every player can only rent up to a maximum of +3 when it comes to looms.
Example: You can rent 1 Masterwork item, or 3 "Tempered" items etc. (So people do not rent out a full set of powerful items. I think it should be something that changes things up but does not give the player too much power.)
After renting the item, you pay a daily price to keep it. Although, the owner cannot take it back until the first 24 hours are up (To prevent people from scamming by taking it away immediately)
A week after renting, the item will be returned automatically to prevent inactive people from losing all their money.
I think this would be a nice feature. Especially considering most clan armories set "Daily fee" to 0. Kinda silly to charge your friend to borrow something, why not make a public version?
Feedback? Tweaks? Name it.