It’s now possible to print functional weapons at home. This is going to progress rapidly now.
Think: global file sharing of designs for servicable weapons, from pistols on up to ?, that can be printed at home. What you can print — from the materials to the size/quality of the object to the completeness (snap together construction) — is already moving forward quickly. The weapons effort will just be along for the ride.
“HaveBlue” has tested the first “printed” firearm and it works. Here’s his site, but it’s VERY slow. It didn’t blow up in his face.