What is a good book to read about 3D printers?
You can learn a lot just by reading the forums.  I'll just list a few that are quite popular...

Reprap Forums - Has a ton of information on DIY printers including build logs and posts dealing with many issues.

Soliforum - Large user base with lots of information. Not sure what it's standing is now that Solidoodle is gone but I'm sure the forum will stick around.

SeeMeCNC - Support forum for SeeMeCNC, has a lot of information for Delta printers and also other printers.

There aren't many books that I know of...Make magazine has done a few issues on 3D printing that you could try to obtain.  I'm not sure what your idea of building a printer is, do you want to design your own or follow someone's instructions and put one together?  Designing one would require some basic hardware and engineering knowledge.

All that said, the best learning experience would be buying a kit and learning as you go.  You'll never read in a book what you will learn from having your own printer.