People who already rent or would like to collectively own pool their resources, either (preferably) the material goods in question or else money to buy them
The goods are collected and, if need be, stored somewhere for use by the customer-owners
If fees need to be collected (for maintenance/repair/replacement, or fuel, or to pay off loans that were taken out to buy the good) they are managed by the customer-owners democratically. Any excess profit is either used to expand the offered services or donated to other local orgs (e.g. Food Not Bombs, community gardens, etc)
This model has been applied to everything from tools to cars to housing and it works great. And if money needs to be collected (rather than surviving solely on donations), the rates are much, much lower than conventional rental services because none of it is going to line the pockets of some bourgeois whose only contribution was having the money to buy up something that people need