Not long ago during a discussion about 3D printing, someone mentioned this turnkey machine approach has been tried at times in the past until the ATF steps in and shuts the operation down.
If anything, these open-access machine shops are becoming more numerous. I’ve gotta go check out the new TechShop in Round Rock, Texas. If it has has adequate CNC metalworking equipment, I’ll buy a membership and see what I can do with a block of aluminum and a USB flash drive.