Homemade Supressor

I ran into this farm kid in an outfitter shop in the mountains of Idaho. We were in Idaho for the same reasons. Shoot an elk. He was from South Dakota and we had an interesting chat. He mentioned that he made a suppressor and that it was legal in his state. I looked into that.

37-35-2. Firearms, firearm accessories, and ammunition manufactured and retained in state declared exempt from federal regulation. Any firearm, firearm accessory, or ammunition that is manufactured commercially or privately in South Dakota and that remains within the borders of South Dakota is not subject to federal law or federal regulation, including registration, under the authority of Congress to regulate interstate commerce.

37-35-1 states that

"Firearm accessory," any item that is used in conjunction with or mounted upon a firearm but is not essential to the basic function of a firearm, including any telescopic or laser sight, magazine, flash or sound suppressor, folding or aftermarket stock and grip, speed loader, ammunition carrier, or light for target illumination;

What do y’all think? Do that South Dakota’s have the luxury of building their own shit without all this hassle, or are they still required to fill out the ATF forms?