You know, I was just thinking, wouldn't it be possible to make a rapid 3d *moulder*, for those bulk parts that you don't require as much precision on (aka, chair)? Picture a stretchable half-mould surface, on a large bed (maybe 50x100cm for a home edition, larger for a workshop) with a grid of little pistons on it that can change it's shape (nothing too high res, maybe one every square centimeter). Picture a second half-mould positioned just opposite, such that the two elements can close off off a 3d space. Such a system could virtually instantly form whatever shape you want, spray the inside with release agent, pipe in a thermoplastic or thermoset resin or wax (for lost wax casting) or confectionary or whatnot, let it set / cure it, and then open up. The pistons could then reshape to ready for whatever shape you want next. If such a moulder would you mess with the two halves individually after they've formed their shapes, you could use it as a composite layup, too. Disposable liners for the mould could be used if sticking / damaging the adjustable mould surface would be a problem.
Wouldn't that be getting awfully close to the potential that mass manufacture currently has? Casting as many times as you want and only having to wait for the product to set? Sure, you'd be limited to relatively simple geometries, but if you need anything more complex, that's what regular 3d printing is for. Hollow shapes could be handled in a two-stage process, first printing out the inner, releasing it, securing it in place, respraying both it and the mould with release agent, then printing out the desired part. I'd think a well-designed moulder could handle that without human intervention.
Hmm, come to think of it, it might even be possible to make a direct metal casting moulder. I know there are high temperature flexible fabrics that can withstand the temperature of most molten metals (various ceramic fiber ones), although I'm not sure whether there are any with sufficient flex for such a role. Oh, hey, carbon fiber and graphite felt are used as a flexible insulating material , that'd probably do the trick.