Where to get chassis for monoblocks?

Hi guys,

I have been going slightly mad (hello, Freddie!) looking for chassises for my monoblock amplifiers (x4) project.
I am basically looking for a 12" (Wide) x 17" (Deep) x 8" (High), aluminium box. As I am only looking at 4 pieces to be made, most places don't give me the time of the day.

I don't mind paying as much as $200 per box if it can approach the kind of quality Mark Levinson/ Krell stuff come in. Anyone know of links?

I am not schooled in CAD, so I am going to draw up a few templates, and make an exact mock-up with (very thick (1/8" plasticized cardboard). Do you think, with this, the machine/enclosure shops would be more inclined to make the chassis?

Thank you!