3.1 - Can you think of any other similarly unenforcable laws which criminalize human behavior? Surely they could write a reprap-themed prohibition without too much trouble.
Sure, the example of how drugs are criminalized a certain human behavior (addiction perhaps) I am sure they could legislate laws to prohibit open source printing.
3.3 - What if IP was just less attractive because sharing your good designs freely gave you direct advertising for your abilities? Could you see someone becoming well known for releasing good designs of useful objects?
Could be, and yes I am sure that if someone released good design of useful objects (like Steve Jobs even though his designs were not free) the general population would make them popular...kind of how the market economy acts.. letting the strong survive in the economy. People value things that are clearly better than their competitors.
2.1 - Do you think any large corporations are in a position to crush a distributed open source movement?
I specifically do not know of any companies that are in position to do so (apparently maybe makerbot?) but I am sure if they really had the motivation and man power to do so, they would.
2.2 - Don't forget the most basic point: That having your own means of production in the form of a miniature factory is enabling in its own right. Good point about sustainability though....that seems to go hand in hand with this sort of endeavor.
2.3 - I've been talking about a list of useful things for some time now. I'm perfectly willing to give you lots of XP for making such a list, but we need to find a place for it on the wiki. Talk to me if you're interested in this.