this post was submitted on 22 Jan 2026
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Yep. The way that is accomplished is that practically all governments that issue paper money add a specific pattern of five circles to it somewhere, often in numerous places. American 10, 20, 50 and 100 bills use repeating patterns of those numbers to disguise it, others hide or celebrate it in various ways. Any scanner, copier or printer is looking for that pattern, and if it sees it, it refuses to print it.

The problem to solve there is "is this 2D pattern present?" It's like asking if the word "soup" is printed somewhere on a page in Courier New, in terms of the computational power it takes to solve; it's just optical character recognition.

Prusa is evidently stupid enough to bake a bitmap image of the object to be printed in their G-Code file, but that could be stopped. The printer doesn't get to see the model file, only the hundreds of thousands of lines of G-Code that it is expected to obey as perfectly as it can.

There are still printers for sale today that run on Arduino Mega-based control boards; you want them to try answering "is this G-Code going to make a part of a gun" as a function of the firmware? Psh.