ya make-em so they accept a Glock magazine... there's millions of them ya make-em so they accept a Glock magazine... there's millions of themYep, there are a lot of them out there:
U.S. Customs & Border Patrol officials have seized more than $2 million dollars of fake Glock magazines in 591 shipping cartons in Savannah, Georgia.
https://bearingarms.com/bob-o/2017/02/17/2-million-fake-glock-magazines/
http://libertynews.com/2013/01/defense-distributed-releases-new-files-for-printing-glock-magazines/
The 3D printed Glock magazines are said to work for at least a 150-200 rounds.
Uzi mags are excellent as well.