Requires bob's library mod.

Currently, this adds 3 new classes to the game (4 if you include the existing class). These have various bonuses and disadvantages added, including a change in starting and respawn equipment.

Fighter: 125% health + healing rate, 75% inventory (-20 slots), 83% reach, 133% run speed.
Miner: 80% health + healing rate, 83% reach and 130% mining reach, 80% run speed, +mining speed, Can hand smelt.
Builder: 80% health and healing rate, 133% inventory space (+26 slots), 133% reach, 80% run speed, 200% build speed.

This mod also adds the Avatar switcher GUI and when you get far enough into the game, you can build new bodies.
The avatar switcher GUI will list all bodies you've build. You can switch to one by clicking on the class picture button. When you press a button, that body is removed from the list, and your previous body added to the end.
When dying, if you own multiple bodies, instead of respawning you will automatically switch to the first body in the list.