I thought this interesting- apparently, one of the lawsuits between the Chicago companies was over mylar heads and patent infringement. The lawsuit was filed by Ludwig against the Solar Musical Instrument Company, which was started by Bud Slingerland and was the factory that made drum heads and the red-badged Slingerland drums in Shelbyville, TN for a few years in the mid-60s, I believe. I read that around 5,000 drum shells were made there.
The subject legal briefs: