>Anyone with any engineering knowledge can see why the 3D printing analogy doesn’t work because there isn’t a fixed set of models being banned.

Also because you can manufacture the exact thing with a lump that you just saw off later (or with a hole you fill with epoxy), or slightly larger / smaller / bent / etc., and it'll be functionally the same.

A functional piece of counterfeit currency needs to be identical to legal currency by the definition of currency; being indistinguishable from the real thing is the only function (otherwise, what you have is a piece of paper).

That doesn't apply to anything whose function isn't "looking exactly like this specific thing".

If the legislation aimed to by museum-grade visual replicas of certain shapes (e.g. an exact scaled down copy of Michelangelo's David), it'd be a technically challenging, but feasible problem.

But the problem they're trying to solve amounts to detecting the manufacturing of pieces with a certain function algorithmically, and forcing that spyware into every machine.

To boot, any form of algorithmic inference of the sort will require much more computing power than a 3D printer ever had.

That's ignoring the feasibility of solving the problem of "can this be a part of a gun", or even the much simpler one "is this part functionally the same as this other part" without giving a false positive on everything (as the saying goes, anything thing is a dildo if you are brave enough; guns aren't much different).

What I'm saying is that zero engineering knowledge is required to understand that requiring machines to refuse to make exact visual replicas of objects isn't the same as trying to restrict function.

I.e. that checking if two flat designs look the same is not hard, but checking if two designs will function somewhat similarly if manufactured is a God-tier problem.

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TL;DR: the only thing you can check by looking is looks.

And while that's all that matters for currency, it's irrelevant for guns.

Hope someone explains it to them legal folls. Ain't no engineering knowledge required for it.

"It takes zero knowledge to" is sadly a statement that works only given common sense,

which too many people are sorely lacking