I'm eventually going to try casting these things out of some of the newer acrylic-like resins I haven't used yet. Not the shitty old ones but the white ones found in SFII, Bomberman 94, etc. If it works it will be way cheaper than 3D printing.
Everyone is so obsessed with 3D printing, and I agree, it's pretty awesome, but it's rarely the best way to make anything you actually care about. These days they use 3D printing a lot to make parts for F1 cars, so those guys obviously have it down, up to and including metal roll structures, but keep in mind that they have unlimited money, a top team spending $100-300 million just to make two cars go in circles for 20 races a year. I work in prototype engine development (not F1, just normal people cars) so we see a lot of RP valve covers, manifolds, etc. Its really good for that, essential nowadays really, but none of these parts would make it 1/100 of the way though the standard motor vehicle warrantee period because that plastic is designed to be printed out first and formost. It's resistance to sunlight, chemicals, vibration, etc all sucks compared to the eventual production part, be it metal or plastic.
For most stuff, and on anything less than state of the art equipment, it's a fuzzy expensive fragile mess. The amateur computer geek angle is the only reason anyone in America would suddenly be interested in some sort of manufacturing. The best uses for 3D printing today are usually those which are part of a much larger (and likely traditional) production process.
For example, I like to build garage kits from Japan. Traditionally these are sculpted by hand then molds are made of the pieces and they are cast in resin. In recent years the process has changed. Now, especially with mecha kits, the parts are designed in CAD and the 3D printed. Then someone has to polish the hell out of the things so they will make decent masters and these parts are recast as resin for the actual kit you buy. Very few decent model kits/parts are coming from 3D printing. They do exist, and eventually that will be the WHOLE scene, but right now it sucks. That being the whole scene will suck too, but that's another thing...