Hmm... I'd be interested to look at any 1A cases regarding that. I'm unable to find any 1A exceptions regarding mere information on weapons. The US is allowed to suspend constitutional rights at border controls, which is how they prevent exporting the information outside the US, but I'd bet dollars to donuts the blueprints/information part is unenforceable as non-commercial speech within the US.

Here's an example of T-shirt with a machinegun blueprint on it for instance, for sale in USA without any checks as to your immigration status [note US law considers a device that induces automatic fire as a 'machinegun' despite the fact the device itself isn't really a gun]:

https://ctrlpew.com/product/yankee-boogle-tee-gatalog-editio...