But how would the actual weights it be made illegal without violating the 1st amendment?

By ignoring the 1st amendment? The US has a tendency of ignoring its constitution whenever it's convenient.

Don't be glib, the 1st amendment is taken VERY seriously.

Im not sure if you’re joking or not.

- the US strictly regulate cryptography https://en.wikipedia.org/wiki/Export_of_cryptography_from_th...

- some prime numbers are considered illegal https://en.wikipedia.org/wiki/Illegal_number#Illegal_primes

I don’t think banning open weight is that far fetch compared to those