Keep researching; before you spend big bucks you want to know what the machine you buy can realistically be expected to do. Your criteria are a bit optimistic, unless you've got a lot of money to throw at this. I still think that as part of your research you should send off some files to be printed, so you can see close up what the results are with printers you're thinking of investing in, and have some parts to test.

The 24" cubic volume requirement rules out nearly all the common and inexpensive printers people around here are familiar with. There are some on the horizon that promise a build volume that large, like the 3DMonstr, but they're not available quite yet, as far as I know.

Even if you print in high-strength materials, with the FDM process that most inexpensive printers use (that's where an extruder lays molten plastic down in multiple layers) the adhesion between the layers is going to be low, so they'll tend to be quite weak in that direction.

Due to the nature of the extrusion process, you won't find any FDM printers that work with materials that melt at temperatures higher than about 325F. If you really want large, strong and heat-resistant parts, you probably should look into CNC routers instead of 3D printers.

Repeatability is not as much of an issue, although these inexpensive printers are quirky and tend to suffer from nozzle clogs, tangled filament, and unexplicable glitches.

Andrew Werby
www.computersculpture.com