The term 'incubator' can mean a whole bunch of different things, and there's no single accepted formula. I guess I'd characterise incubators in general as
- Objective-led - where investment is being channelled to startups, often in a particular technology area, in the form of (say) subsidised space with access to expertise, funding etc
- Facility-led - where a (public or commercial) owner of office space decides to create a 'startup-friendly' environment (sometimes with discounted terms in exchange for equity)
- Investor-led - where one or more prospective investors create programmes to talent-spot startups and push them through acceleration into investment
- Skills-led - where what's on offer is essentially hands-on learning with access to resources or people with relevant experience
- Mentor-led - where a single mentor or group 'adopts' a location and supports (all or selected) founders and projects
I have direct personal experience of all but the 'skills-led' type, in both commercial and academic (targeted investment and IP commercialisation) contexts.
So first, you should think about what resources you have available (cash, space, connections), what existing communities there are in your area (tech groups, funding sources, seasoned entrepreneurs etc) and what objectives you have.
It sounds to me as though you're describing something you'd like to be part of. That's a valid starting point, and I have some suggestions for you.
First, find a location that's set up as both a social and working hub. That could be just a coffee shop with WiFi. If somewhere is already functioning in this way informally, start there.
Second, socialise your idea with as many people as possible who are interested, and flesh out what would be great, and what you would need. Start with existing groups, and if there isn't one that covers startups, band together with like-minded people and found one.
(I co-founded the Pitch & Mix format in Cambridge, and we'd be happy to help you use this in your area - it's essentially a re-think of the OpenCoffee idea with just a little more structure, and we are helping other groups get going around the world.)
And then treat this as a startup situation. You need a co-founding team, who share the vision and are ready to commit. And you need to find people who'll want to access the proposition you create, in a way that is financially viable.
Good luck! Start small and build up gradually. Beware just copy-catting a formula that may not work in your context. And accept that some of your questions will be answered one way to start with, and may develop another way over time.