What it does require is time and money.

Developing a patent application requires filing fees, which vary but have never been trivial.

It requires either the legal knowledge to draft the patent oneself or the funds to hire a patent attorney.

It requires the time to think through the design in sufficient detail to describe it precisely in the technical language that patent applications demand.

And it requires the emotional and financial resilience to sustain the effort over the months or years it typically takes for a patent application to be processed.

Mary Kenner had the thinking capacity, the observational acuity, and the persistence.