[EricH]

If you're going to build something for practice, make it a fairly simple drivetrain.

Protip: Don't go complex in the drivetrain your rookie year. Go with the KOP drivetrain.

You can also look in CD-Media's whitepaper section; there are a number of papers on arm or drivetrain design; take a look at JVN's mechanical design calculator. (Or... any paper JVN has posted there...)