If it's all sheet metal-esque pieces, where you could suffice with just laser cut features and/or simple bends.. then you should take a look at OSH Cut.
They have a fairly powerful platform -- instant quoting from uploaded design files, 2D/3D views, DFM feedback, good turnaround times, etc -- and the pricing isn't half bad for prototyping... but might not be as good for large-scale runs compared to bigger shops where you can nail down volume pricing discounts.
They have a fairly powerful platform -- instant quoting from uploaded design files, 2D/3D views, DFM feedback, good turnaround times, etc -- and the pricing isn't half bad for prototyping... but might not be as good for large-scale runs compared to bigger shops where you can nail down volume pricing discounts.