I ran across an article called “Beyond State Control” published by SmallArmsSurvey.org.
The report takes up 128 pages, and does a pretty good job of showing spots where gun control legislation has failed. Page 80 shows production of submachine guns in Canada:
Canadian authorities have also seized significant numbers of craft-produced submachine guns from criminals. In December 2015, Toronto police found what was described as a ‘Tec9’ sub-machine gun in an abandoned vehicle (CityNews, 2015). The gun, actually a craft-produced copy of the Intratec TEC-9, was one of many produced at a plant in Montreal, Quebec. The Royal Canadian Mounted Police have since traced more than two dozen of these to 18 locations across Canada (Berthiaume, 2018). The sub-machine guns in question were produced at a metal-working factory and feature two CNC-machined polymer halves used to form the frame of the gun, a distinguishing feature of other TEC-9/DC-10 copies (see Image 38). The barrels were threaded to accept craft-produced suppressors, also made in the factory. Two factory directors were charged with firearms offences; they had reportedly told factory employees that they were manufacturing parts for paintball guns (Berthiaume, 2018).”
Their illicit product looked something like this:

Earlier, the authors explain why the submachine guns are so common as what they term “craft-produced small arms: “Sub-machine guns are perhaps the most widely documented craft-produced small arms in circulation (ARES, 2018; ImproGuns, n.d.). Their high rate of fire and low cost make them attractive to organized criminal groups. Often chambered for the common 9 × 19 mm cartridge, they are frequently based on Second World War or cold war designs, such as the British Sten and the US M3 ‘grease gun’. As such, they almost always operate on the simple blowback69 principle, firing from an open bolt (ARES, 2018; Jenzen-Jones, 2017a). Pulling the trigger releases not the firing pin but the entire bolt, which picks up a cartridge from the magazine, chambers it, and fires it by means of a fixed firing pin. The bolt is then ‘blown’ backward by the fired cartridge, such that the empty case is extracted and ejected, while the bolt is returned to the rear, where it is ready for the next shot. These weapons require none of the complex machining and engineering needed to create a reliably functioning locked-breech firearm, and they can be relatively safe to operate.”

The photographic quality is probably lower than the machining quality – while these examples were taken from a protestant group in Northern Ireland, I suspect the Provisional IRA has equally skilled folks in their workshops.
Another article, from the same folks in Switzerland is “Craft Production”, found here.
It begins with “Craft production of small arms refers principally to weapons and ammunition that are fabricated largely by hand in relatively small quantities. Government authorities may tightly regulate and oversee these artisans’ activities and outputs (expensive replica antique firearms legally produced in the United States are a good example). Often, however, this material is produced outside of, or under limited, state controls. These weapons are often used in crimes and against government targets.”
The problem with legislating gun control is that some folks out in the real world are better at making guns than the folks trying to stop them. If they’ve been making submachine guns in Quebec, I suspect the idea of shutting down ghost guns by legislation is closing the barn door after the horse is in the garden.