You could be. Just discussing the issue with a friend is not a violation; the violation would come in if you drew diagrams, laid out templates, etc., when you knew or could reasonably assume that these would be used by your friend to make an auto weapon. Your action could be construed as being an accessory to or part of a conspiracy to commit a felony, that is, the illegal manufacture of a Title II firearm.
For a comparison, if a friend and I discussed bank robbery in general, there would be no crime. But if we drew diagrams, lined up a getaway car, mapped out an escape route, and wrote the note, there would be a conspiracy even if the robbery never took place. If my friend pulled off the robbery, and if I had done those things for my friend, I would be an accessory, even if I did not actually go near the bank.
The issue gets tricky; AFAIK, the outfits peddling templates have not been bothered, and I do not know of any prosecutions where only paper was involved.
Arrest and prosecution usually depends on whether or not the illegal gun is used in a (another) crime, or whether the bank is actually robbed. Then prosecution is certain, and everyone involved is in trouble.