Tim, I’m hoping to do something like that. Have a build zone, a super detail zone, paint zone with airbrush and finishing spot. Basically, two short sides and a longer one.
My old spray booth will be set up and ducted. However, in warm weather, the windows are going up and whole house fan/attic fan will run for the paint sessions, no respirator because pulling 10,000 cfm out of a 250 to 300 square foot room, no fumes or particals accumulate in my experience. I’ve ran a similar set up ~30 years ago and it was the best I’ve used. In the winter, will use the spray booth & respirator and vent fan as previously. My limited with a respirator on is about an hour and half max, 45 minutes ideal. I used to be able to airbrush ~4 hours plus in one session with the attic fan…I doubt my knees will allow that now days but who knows.
Steve, yes, I’d like to do epoxy on the garage floor for sure. The exposed OSB needs a sealant or painted so it does absorb moisture etc so after that’s wrapped it will be floor time. I’d like to be able to keep the floor unstained since we’ll do family stuff here too sometimes.
Greg, agreed sealing is probably the best option for me. The fancy floors are pretty slick with the interlocking tiles etc and being able to do patterns but I’m not sure I need that sort of thing. I’m afraid it might have tripping hazards for some of the older family members even with beveled edges etc
One thing, actually two things I’ll have to add are a pair of cat trees 
one in garage and one in hobbyroom for Kali-Katt. She’s on record wanting a pet door in the laundry room door to outside and the hobbyroom door too. She’s getting a fenced backyard so she can do what she wants…said my catio idea was pure Bull$#i+
And its starting to look more like part of the house…
