You can make a zip gun from pipes and rubber bands right now and it would shoot in a pinch but if you have one assembled in your home without proper paperwork you're going to jail for a long time when caught.
If an NFA tiem yes, but in most of the country you can manufacture other firearms without doing any paperwork whatsoever as long as it is not for resale.
I suspect someone will make one with stock included similar to CAV arms and that will be far more successful that the others. The one that went 20 rounds was made with the wrong material on the wrong machine from what I gather. The 80+ round one was made months before it.