Why are home made lamps a non-starter
Because roadways are public, and vehicle lights, being safety equipment, are legally regulated in detail as to their design, construction, operation, performance, and durability -- and this applies even to lights that aren't required, such as auxiliary lights. The specs and requirements are rigorous and require a great deal of specialized knowledge and equipment to meet and test. You can't just throw something together and declare it's whatever kind of light you want it to be.
Purpose? I dunno just having fun.
It's fun to play with lights, yes. That kind of fun has to be confined to lights that can't affect the safety of others. Obviously nobody can reach through the internet and stop you from doing whatever you're going to do, but
Rule 11 of this board prohibits advocating/discussing illegal or dangerous activities...including homemade car lights.
you can't even put your high beams on because it blinds opposing traffic
Right...and the same applies to the auxiliary lamps you have in mind to build.
