instructions can make a can and mount it on an AR-15 in a day or 2. There's some tricks of the trade that let you get nearly all the work done, by 3-4 different shops, machining and welding, and only you know what's what. For instance,if a shop welds a plug into each end of a 20" long pc of tubing, it never occurs to anybody that maybe what you are really going to do is cut it in half.
Ditto the guy who threads both ends, for 7/8x14. Another shop of course makes the adapter, which threads into the end of the can, and the ID of which matches the 1/2x28 TPI of the threads on all AR muzzles. Nobody who made the baffle forming tool 'kit" would have a clue what it really was, but you could always have 2 shops make it, if you are worried about such things.