Really nice. I've got an old Briggs and Stratton 5hp tiller motor you could mount on that thing.

Good thinking...  It needs disc brakes.

AWESOME Idea!!! Btw Derek, how do you like that Eastwood MIG? I learned how to weld on a craftsman (made by century) 90A welder which I had used for number of years. I recently started using a Millermatic 135  it welds smooth as butter, a night and day difference. No more hoping despite correct technique that the weld is gonna turn out nice. Now I'm looking at getting a Millermatic 211. 

Interesting, my Craftsman had a tweco gun which had the gas valve in the gun and two trigger positions, half trigger operated the gas valve, and full trigger fed the wire. It was nice because you could voluntarily keep the gas flowing over the weld for those really hot welds (or puff out some flaming paint/undercoating near the spot you were welding). That's one thing I miss about the Miller. Having the gas flow another 3 seconds involuntarily seems a bit much though. 

Well........IF you cool the MOLTEN PUDDLE too quickly it will " suck-a-butt-hole" in the weld.(HEY!! EZ censer....that's what my welding instructors called it and I'm just repeating it!) Which is no big deal for regular old sheet metal repair welding butt a no-no for X-ray type welds.
I have TRIED to make them^^^ (see above) just for fun and have not been very sucessful. Really much to do about nothing.
I think TIG welding must be more of a problem than MIG because the TIG machines have an adjustment(its called "weld de-cay".) to prolong the Argon gas coming out...or shorten  the time it sprays. MIG must be pre set  in the machine.
I guess you COULD regulate the amount of gas coverage to try and save gas.
Inside a shop the gas coverage can be way less than trying to weld outside where the wind may effect the gas coverage.
6sal6