Jan sent me a card all the way from Australia asking me to comment on not-for-profit sewing rooms. Not that I have any intimate experience with such an entity, but that won't stop me from putting in my two cents worth!
I am very fortunate to have a studio space away from my home. It actually belongs to a clothing designer who is off working in film, so she has sublet it to me. The absolute best thing about the space, other than it being in 1000 Parker, the coolest artist building in Vancouver, is the CUTTING TABLE! 8 by 16 feet of glorious flat space! If you sew, you will appreciate how luxurious having a cutting table can be after years of making do on the kitchen table or even the floor!
Having a separate space is good for many other reasons too. There is room to organize my fabrics and supplies. I can shut the door at the end of the day and leave the mess where it is. Paying rent is motivating in that, being Scottish and all, I want to get my money's worth, so I actually come in on a regular basis. (And of course I can deduct the rent as a business expense.) I feel more professional and legitimate having a proper workspace.
So that's where it starts, I think. If you're thinking of creating a sewing space for others, make one for yourself first. In my own case, once people find out I have a studio and I sew, they often ask if I teach. This is an avenue I haven't developed at all, but it would be easy to put a sign out and simply offer weekly sewing workshops, where people might pay $5 or $10 for a evening of shared information and an opportunity to use the cutting table or machine, or learn hand sewing skills. I think that would be fun, and it wouldn't take long for the group to start covering my rent.
There are definitely lots of for-profit sewing spaces out there. Many cities now have Stitch Lounge type shops. Generally they offer plenty of classes, and rent out time on the machines for $10/hour or so. Running a shop like this would require a good head for business (or at least the willingness to learn), and all the rewards and headaches of having your own business.
I like the co-op model myself. Get together with a few other skilled and enthusiastic people and offer open studio time, workshops and classes as you choose, figuring out a formula for buying a "share" of the co-op. Members could use the space at a reduced rate, while the general public might pay more.
Basically, you want to cover your expenses, have some money in the bank for future growth, and be enjoying yourself. The non-for-profit thing gets old really fast when it begins to feel like work. I think one could set up an inviting workspace with a half dozen machines (and good old Singers from Craigslist work just as well as middle range new machines for learning on!) a cutting table and a couple of irons for a fairly minimal investment and you'd be off! There could be the possibility of partnering with your local arts council, community centre or guild if you don't want to go it alone.
I don't know if that covers your question, Jan, but let's hope it starts a bit of a dialogue! I'd love to hear from others as to what experience they might have with communal workspaces or shared sewing studios.
And I'll take this opportunity to plug once again the joy of sewing with others. The ideas flow, laughter and tears are shared, friendships are made. The practical pleasure of making something yourself is amplified by the support and companionship of a group.