Why are you even bringing in the government into this or the constitution? The owner of the printers didn't want the guy manufacturing weapons using his leased printers. The government didn't step in and take away the printers, a private citizen who had a private company did. Sure his explanation has holes in but he could simply say that he doesn't want his printers used to manufacturer guns and revoke the lease. The individual who wants to continue manufacturing weapons using printers can go find another private company or private citizen to lease from.
Now had the feds come in and snatched up the printers because he was manufacturing weapons that is an issue with the constitution. UNLESS, he was selling the weapons he manufactured or was transferring them because this requires an FFL license.
All we have are two private parties who are at disagreement on a business operation and thats it.