OT Non-standard dovetail

An aquaintance intends to install a solar panel sometime in the Spring. The attachments to the roof use aluminium channel etc. of various sizes, and he needs some more making.
Anyway, I offered to make some of this stuff ( 13 mm x 17 mm) only to find that the channel uses a non-standard dovetail. As far as I can tell, it's something like 76 degrees !
I intend to make a cutter out of silver steel, but wanted to ask first if anyone knew about these things :-
Q1. What angle is the dovetail ?
Q2. How accurate would it need to be ?
Thanks, Peter W.
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