The easiest place that I know of to find such files is Odysee. Search for AWCY (Are We Cool Yet) and Deterrence Dispensed. And search for people showing off 3d printed guns. They will sometimes include tips for printing.
As far as printers go, don't cheap out. Things like auto-bed-levelling and a direct-drive extruder are really helpful. Maker's Muse on Youtube is a great resource for 3d printers in general.
Probably the wrong place to ask a question like this and kind of smells like you are a government plant to try and get Bitcoin people associated with illegal activity and undermine the great things this movement is trying to accomplish.
In the US, creating and sharing files for 3d printed guns is 100% legal. Those activities are protected by the 1st and 2nd amendments to the US Constitution.