Source: https://www.mass.gov/news/public-safety-notice-for-3d-printing-of-weapons
Timestamp: 2019-04-18 22:18:42+00:00

Document:
Plastic Weapons: Weapons made exclusively from plastic or that otherwise cannot be detected by an x-ray machine or walk-through metal detector are unlawful, as are “covert weapons,” weapons designed to look like something other than a gun (e.g., a key chain, pen, or cigarette lighter). They cannot be sold, transferred, or possessed. M.G.L. c. 140, § 131N.
License Requirement: An appropriate state-issued license is required to: (1) possess or carry a weapon; (2) sell, rent, or lease a weapon; and (3) possess or purchase ammunition. M.G.L. c. 140, §§ 122B, 129B, 129C, 131(d); M.G.L. c. 269, § 10(a), (h).
Reporting of Sales: Sales and other transfers of weapons must generally be reported to the Department of Criminal Justice Information Services by the transferee at the Massachusetts Gun Transaction Portal on the internet, unless the weapon is purchased from a licensed dealer. The information required includes the caliber, make, and serial number of the weapon. M.G.L. c. 140, § 128B; 803 C.M.R. 10.00.
Safety Requirements: Only firearms that are on the Executive Office of Public Safety and Security’s approved firearms roster may be sold by a licensed firearms dealer. Currently, no firearms made with 3D printing technology are approved for sale in Massachusetts. M.G.L. c. 140, §§ 123, clauses 18 to 20, 131-3/4; 501 C.M.R. 7.00.
Safe Storage: All weapons must be securely stored. There are enhanced penalties for weapons left unsecured around minors. M.G.L. c. 140, § 131L.
Assault Weapons: The sale, transfer, or possession of any “assault weapon” is prohibited. Any weapon that meets the definition of an “assault weapon” under Massachusetts law, whether made in whole or in part out of plastic, is prohibited. M.G.L. c. 140, §§ 121, 131M.
The Attorney General’s handgun regulations generally prohibit the commercial sale of handguns without certain safety features that decrease the likelihood of accidental discharge and injury, including to children. These regulations apply to handguns made, in whole or in part out of plastic, and subject individuals who violate the regulations to civil liability. M.G.L. c. 93A, § 2(a); 940 C.M.R. 16.00.
1 “Weapon” is defined in Massachusetts as “any rifle, shotgun or firearm.” M.G.L. c. 140, § 121.
2 There are also numerous provisions of federal law applicable to these weapons. They are not included in this notice.

References: § 131
 § 10
 § 128
 § 131
 § 2
 § 121