One "stamp" per toy. On your ATF application, you must provide the equipment serial number, in addition to local LE chief sign-off approval/fingerprints/mug shot. Your Class 3 dealer submits, ATF approves, equipment is sent to the Class 3 dealer from mfg. for your pick up, with whatever fees you and he agree for transfer.
Pretty straight forward. Suppressed full auto 10/22, $200 for weapon stamp,$200 for suppressor stamp. It is a document having pic and stamp of approval from ATF for each widget. Safeguard originals, keep copies with you.
And, don't even be caught with unregistered, serial numbered or not Class 3 designated widget. It will certainly bring you alot of misery in fines and prison time.
Hate to pop the bubble, but strictly enforced. One stamp per Class 3 designated item.......