As Mrmike & others say, the costs will probably outweigh any profits.
The other issue is enforcement, e.g., Neomega are posting on social media that a Russian(?) co are blatantly copying his stuff & passing it off as their own, but there is no economic way of enforcing his rights.
There are periodic spates of chinese companies selling bad quality knock-off copies of Hornet & various other OOP figures on well-known auction sites, who sometimes will delete the item listings.
That said, I think that it is rare, as individuals will find the cost of copying your items exceeds the cost of buying them directly, nefarious individual companies excepted.
Bottom line is, you can use 3D printers to create your own masters for casting, or even sell them through sites such as shapeways, but you have little control of what happens after it leaves your hands, but if you got a better mousetrap it will sell.