I've built a new "Builder class player.". How do I switch to it? I only seem to be able to place it, and if I do, it becomes a npc building thing? I can't even pick it up again?

oh, apparently you're supposed to go kill yourself.

LOL, don't kill yourself. there should be a button in the top left corner of the screen that looks like the player. click on that and it shows you all bodies. you can then click on the icon for any of those to switch to it.

Clicking that button brings up a little window that says "Avatar switcher GUI". Is there some option to enable?

[Deleted]

Clicking that button brings up a little window that says "Avatar switcher GUI". Is there some option to enable?

You need to build new bodies to switch to them. you can have more than one at a time.

Once you pick a class, you are that class forever. The only way to change it is either to die and pick a new class, or build a new body of a different class and switch to it in the avatar switcher... or die and you automatically switch to any other existing body.