For Sale: Mamiya brand metal case for Mamiya 6 outfit. Factory cut-outs in foam for the Body, 50,75,150 mm lenses and lenshood or filters. Excellent condition.
The M7 is not much bigger. I'm sure you could cut out the foam to fit.....
It is worth remembering that the case slot for the body is for the body only not w/ lens attached....as the M7 doesn't collapse.