Another interpretation can be that you can still purchase them freely at any gun store or via the internet. The key to all of this is sentence 2:
"§134- Manufacturing, purchasing, or obtaining firearm parts to assemble a firearm having no serial number; penalty. (a) A person who is not licensed to manufacture a firearm under section 134-31, or who is not a dealer licensed by the United States Department of Justice, shall not, for the purpose of assembling a firearm, purchase, produce with a three-dimensional printer, or otherwise obtain separately, or as part of a kit:
(1) A firearm receiver that is not imprinted with a serial number registered with a federally licensed manufacturer;
(2) A firearm receiver that has not been provided a serial number that may be registered in accordance with section 134-3(c); or
(3) Any combination of parts from which a firearm having no serial number may be readily assembled; provided that the parts do not have the capacity to function as a firearm unless assembled."
...meaning, if you put a serial number on the piece of plastic/metal FIRST before you begin any milling or drilling, you are in compliance with the law as written.
And while they have attempted to define a firearm receiver..."Firearm receiver" includes any object or part that is not a firearm frame or receiver in finished form but that is designed or intended to be used for that purpose and may readily be made into a firearm frame or receiver through milling or other means." they have never defined the term readily. And that has been asked for eons and as for intent, if I go into Home Depot and purchase a 10x12 piece of 12 gauge sheet metal with the INTENT to make an AK rifle out of it, can HD sell it to me? A piece of steel tube to make a STEN. They aren't an FFL , but are selling firearm parts.
Poorly written laws have unintended consequences