Very nice, George. Thanks for sharing. Maybe you did some prior experimenting before landing on Garolite G-10 FR4 for the distributer cap? I'm quasi-aware of its temperature & dielectric properties. And obviously its working for you. Did you try other materials & conclude they were unsatisfactory for one reason or another?
Reason I ask is I'm familiar with composite molds. Making a shape from say 3DP & casting a distributer body off molds from this shape is do-able in my shop. Now it may serve no net advantage in the end but the option may be there. But there lays the crossroads - type of epoxy, glass filler etc. I have seen pics of running model engines with clear (some kind of plastic) maybe to help monitor spark issues? Anyways, just curious about your comments in this regard.