First you start with a SpaceX fairing which is made in two pieces...
You fill it with just two things (one thing, see update) making it very light. First is lots of plastic just thick enough to hold one full atmosphere. When inflated this creates a huge interior volume. I'm talking bigger than anyone else has imagined. Much bigger than the BA2100 and less mass so it can be launched on the F9. Attached to this plastic would be multiple very low mass airlocks allowing many ships to dock. These would be properly positioned by being attach to the plastic so everything comes out right after inflation.
This is not a completed station. What it is, is a work area for making a completed station. On a separate launch go the construction workers and materials. They laminate the plastic with multiple layers like Bigelow's habitats now have. They furnish the station with cabins and life support equipment. Let's call this hands on science if you need a justification.
By starting with the fairing you don't have to figure out if your design fits in the fairing. It does. You can also have windows built into the fairings so that element of construction is not required in the plastic. Actually the fairing could have other elements built on the ground that you don't want the construction workers in space to have to deal with.
The cost of this thing should be such a small percent of the cost to launch on an F9 that any nation that wants a space station could now have one. They would all construct it in any way they like as part of their own nations research. So countries, would you like your own space station with more volume than the I.S.S., send as many astronaut researchers as you like at a millionth of the cost?
Update: Even simpler... forget the airlocks, it's all just plastic folded inside and properly attached to each fairing. You built one airlock in each fairing half. If you want more, DIY.
BTW, this plastic could inflate to almost any shape required even before any construction.
Update: What kind of plastic works? I'm researching now. There's also rubberized cloth and latex as possible alternatives.
Some young people doing research.
Space habitat project. Introducing us to Vectran.
A how to build article.
From the killing two birds with one stone department.
Update to answer uzivatel's questions:
Imagine you've just docked on one half of the fairing. It hasn't been inflated yet, but now you start the process. It's inflated to one atmosphere and is now huge. One astronaut crosses in while the rest wait in the Dragonrider. The plastic already has points for connecting lines so that astronaut is not just floating around (well, once we stop him/her from just having fun floating around.) They could have compressed gas thrusters for moving around but do not really need them. Update: Docking will require the ability to align. The Dragonrider has the ability built in but the station will need something as well. Outside the box ideas? Before inflation it isn't that big... perhaps a sticky rope would do the trick? If it's tumbling that may be all you need to stop it. Maybe not.
Sharp items? It's the same answer the doctor gives when you say "it hurts when I do this." Don't do this. Don't poke the plastic with sharp objects. But suppose you do. It's inflated to one atmosphere and is now huge. It is puncture resistant. If it is punctured anyway it will take a long time for the air to bleed out even from a big hole. They will have time to patch it. Once laminated that problem pretty much disappears. It's no different than the protocol on any space station.
Heat? Reflect the heat away. You'll note others using aluminized plastic. We might use something else. The goal is something low mass and flexible not as a final surface but something the final surface can be laminated to. Heat plastic enough and it will melt. Actually, that's true of just about every material. Yet, we handle it. Read about skylab for an example or the examples I've already provided.
Radiation? The good news is this isn't deep space, it's LEO. The earth protects us from most radiation in LEO. Anything with a high hydrogen content is a good radiation shield. Bigelow habitat skin is about a foot thick. We're going bigger than Bigelow. We can make the walls as thick as we like probably using a spray on foam sandwiched with other materials.
Repairs? Having constructed it, they should easily be able to repair it. How does Bigelow intend to repair his. Whatever a thing is made of it will have it's own method of repair.
Once prepared the astronauts will be able to take off their space suits and work in comfort. The final product can be any level better than our current stations. The customer is free to choose.
Update: Thoughts from some real rocket scientists.