[fargus111111111]

While I do share the concern about the pvc tank that others have mentioned, I would not be at all concerned about the pvc barrel. I have seen many t-shirt shooters (including our own) with pvc barrels that are performing wonderfully. The pressure in the barrel is relatively low and only lasts a moment therefore the plastic is plenty strong.
Over all it looks really cool. I love robots like this that look like something more than just a robot, not that just a robot isn't cool, it is, but the extra work to make a body for it just makes it look that much cooler.