Cool! -

However the current Canadian Government & RCMP would call that manufacturing a firearm without a license. Then, possession of a non-restricted firearm without a license.
Then, after confiscation, they would have Forensics branch convert those plastic parts into a real firearm by replacing the action and barrel for the charges to stick and they most certainly would.
Still, pretty cool!
A fellow in Alberta has received 13 firearms charges for doing just that on a 3D machine of making a rifle, along with also making a handgun, which is a restricted firearm, along with producing a silencer on his 3D machine - possession of a prohibited device - along with 3 charges for attempting to sell all of these devices and firearms - without a license.
13 separate charges for making a handgun and a rifle along with a silencer - all out of plastic on a 3D machine.