To clarify, the only plastic part on the Hyrel Printers is the cover plate on top of the spine. This is ABS at 200 microns, and on the Engines it holds the pneumatic fittings for the guide (not bowden) tubes. Everything else is made from sheet metal, stainless steel, or aluminum stock.

As I sent via PM, other than the build volume (a little over 20x20x20cm), the Hyrel printers meet your specs. While our default nozzle size is .5mm, we also offer a .35mm - but lower quality filaments can clog the .35; the .5 is much more forgiving of lower quality filaments.

We have users who make 50+ hour prints regularly.