Mountain Bike Build Sets

is it possible to Frankenstein a regular mountain bike?
i have 3 mountains bikes which all have their own problems. I was wondering if i can salvage the frame of 1 bike and than just build around that bike with the other bike parts and make a franken-bike. I already have a good set of bike tools and a good socket set. Is this possible to do?
I used to do it all the time.
I never had a new bike growing up, we used to steal (I hate to admit that) parts from all over the place to make a bike work.
How to build a fixie from scratch Part 1 Bottom Bracket and Crank set live4bikes

