I was into the model railroads. N Gauge to be specific. In our old house, had 2 rooms dedicated to hobbies. The 'train room' was 12'x10'. Had a 5' x 10' train platform. Really nice setup, could run 6 trains at once. They are now all boxed up in storage.... no room in our new house.
My other hobby is RC planes and surface vehicles. At one point, between my two sons and myself, we had a total of 46 planes of assorted sizes and types, 3 nitro powered 4x4 trucks, 4 electric trucks, and a nitro powered sno-cat. They had a dedicated room that was 12'x18'. Looked like a hobby store!
I /we downsized, now only 12 planes and the trucks. I have been rehabbing and updating the power systems on them over the past year. About half are ready to fly this spring.
Then , of course, is the tool collection:
Then there is the landscaping and gardening that I get involved with the wifey. She grows trees, plants, and shrubs from cuttings and seed. A constant growing, transplanting, more growing, and final planting. We have about 12 willows, 8 honey locust, and 30-40 plants to get planted this spring.
Sometimes, I do consider this more 'work' than a hobby. The fun part about it is that I get to use the tractor a lot!