> My advice is for the OP to make his build system GPLv3 licensed and sue anyone who willfully violates that license. Except that filing a lawsuit costs money,

> My advice is for the OP to make his build system GPLv3 licensed and sue anyone who willfully violates that license. Except that filing a lawsuit costs money, and if by nature your product is free, where are you getting the money for said lawsuit, and what damages are you suing over? You might be able to get a cease and desist order for copyright, but then what?