Since the JBL Master Reference Monitor thread is so massive I'm staring a thread that I and others can document our M2 DIY process if the. Here are some links that I was able to reference. Thank you for all of your contributions that made my and others project happen.
Schematic of the M2 - Note: C2 in the schematic shows a value of 33.3uf, this is a typo. the correct value is 3.3uf
DSP File
Inside the M2
Outside the M2
M2 Dimensions
Horn Mounting
Horn Mounting pt2