Originally Posted by
dharmic
Ambitious, indeed.
Most 3D printers don't get anywhere near the build volume, so you'd be looking at a custom and quite large printer to begin with. And they're not built that big for a couple of reasons:
1. If you start to factor in your time, it's just not going to be worth it. A 2 litre part can take 24 hours to print, a bumper is going to be more like 2 weeks to print. And you cannot leave them unsupervised - if anything goes wrong and you're not there you're looking at some real fire hazards.
2. Physics. The plastic cooling after it's been extruded creates some serious internal stresses in the part. Often, on a smaller bed, they're enough to buckle the part enough that it pops off the print bed. Now you're talking about something an order of magnitude larger than the usual printer and I'd be thinking the buckling would be inevitable.
3. Forget production finish. Even the finest print at 0.05mm layer height (which will be even slower again) leaves a pretty rough finish by comparison to a moulded product.
Materials - I use ABS or Nylon for smaller structural parts. Both have strengths and weaknesses and quirks which add complications to the printing process.
I think you'd be much better off for stuff on this scale looking at a router to make moulds and either lay glass or look at vac-forming ABS or HDPE sheet.