I don't really have a hobby...unless you consider eating a hobby. Maybe cooking?
But, George (Mr. Studiogirl), who like you can pretty much build or fix anything is a "tinker" and finds seemingly endless pleasure dinking around the garage, building and repairing bicycles. He "rescues" bikes from around town...abandoned, chained to light posts but missing the wheels, etc. He fixes them up, sometimes making one good bike out of the parts from several, and then sells them on Craigslist. Doesn't really pay for his time, but usually covers any parts he has to buy, and the buyers get a good price (most buyers are college students).
I can't count how many motorcycles, scooters, mopeds and bicycles have passed through our garage! Anything with two wheels, though I've noticed he's a lot less interested in motors these days.
He has also dabbled with stained class and other artsy-fartsy stuff...all very cool. I did pottery for a while...both kick wheel and electric. I liked glazing the best...fun to play with color and texture. (And it gave me a lot of stuff to give away!)
Remote-controlled anything also sounds like fun to me...boats, vehicles, planes...rockets...you can build all those and then go play with them! Especially two-stage rockets!!!!
I used to love photography, but now in the digital age, film, enlargers, light-sensitive paper, chemicals...have all gone by the wayside. But I would still someday like to have a darkroom and do some large negative, black-and-white stuff.
Two other things I'd like to do, but probably won't unless I move to the country, are keeping bees and having dairy goats. But now we're back to food.... Oh well, at least I'm predictable!