Does a "Poor Man's Patent" actually hold up in court?

[Fehourempard]

I’ve finally built a working prototype for a new type of bicycle lock that I think could be huge. I’m terrified of showing it to manufacturers because I can’t afford a full utility patent right now (quoted $10k+). My uncle told me to just mail the blueprints to myself in a sealed envelope to prove the date of invention. Is this "Poor Man's Patent" a real legal defense, or is it an old wives' tale?

 

[Zucososh]

Forget the envelope trick. If you are tight on cash, focus on a Non-Disclosure Agreement (NDA) before showing your prototype to anyone. Most reputable manufacturers will sign one if they are serious. If they refuse to sign an NDA, that is a massive red flag that they might steal your design.

 

[Youst19]

I wasted six months trying to do everything myself because I was scared of the legal fees. I looked into those "all-in-one" submission companies that promise to handle the patenting and marketing for you. It sounded tempting to just hand it off. However, before I signed anything, I did a deep dive into the industry. I read through countless Invent Help reviews and noticed a pattern of people spending thousands on research reports that didn't actually secure any intellectual property rights. It convinced me to scrape together the money for a registered patent attorney instead. It’s expensive, but buying a fake sense of security is worse.