skywave... would hate to rain on someone's parade of raining on someone elses parade....??? however i believe you have missed the point of this DIY?
for one ribbon transducers are incredibly simple devices to build, with ZERO coils of wire in the motor assembly,
they operate under the principal of current being induced into a pleated foil ribbon suspended within the flux of two magnets and sent through a 20-50:1step-up transformer
(not exactly rocket science)
being the only "complicated" component in a ribbon mic, this step-up transformer could be tricky to diy ,but certainly is not impossible
furthermore the author had stated that there are off the shelf options they would take advantage of...
(go with the lundell btw?)
although ribbons don't have a great deal of output, with a proper mic preamp one can capture nuance and detail and clarity that rivals some of the most expensive large diaphragm condenser mics meticulously crafted in labs not unlike NASA, in spite of a deceptively crude design
sidenote- Royer labs, one of the widest known ribbon producers worldwide is much more like an artisan/craft shop than a "large precision facility"
anticipating good things from this build
keep up the good work !!!
and above all,
have fun with it!!!