For those of you who are too young to know, the Jahns' fence diagram that I sent previously and Figure 5 of Jahns and Ewing (1977) were drafted by hand with drafting pen and rub-on stencils, as were the hundreds of geologic maps that were published as part of the WWII mapping effort in the USA by the USGS (e.g., Cameron et al., 1949). David London Pegmatite Interest Group: https://msaweb.org/pegmatites/