I'm not sure where your going with this, no one will be printing the AR part at their house...
These will be plans that get sent to a multimillion dollar facility to be used on a very high end machine... So that the end result is something a consumer can just slide and screw in with readily available components on the market.
And I'm not even sure this will use the method where you shave down 1 big block into something , i think this incorporates the method of building it up from a heated material... Hell maybe even both. All I do know is, he has the facility/ staff to do measurements for multiple weapons and components... And a printing partners supposedly lined up.... He is doing the heavy lifting to make it very easy for someone to buy the plan and order the component, ( apparently that part is very important legally),... And then they assemble it themselves