Currently, parts like Toruses (Rings), Cones, and Triangle Corner Wedges are very hard or unreliable to make (especially the cone). Having them added to the existing Block, Ball, and Cylinder shapes would be helpful.
It was stated that more primitives would be added A WHILE ago but still hasn’t been addressed.
there is a csg plugin that can do this
Main issue is the triangle count is massive, and being solvable is not a guarantee, and not to mention takes up file space, network space (for loading), and computation time without the ability to change the scale later ingame.
I have tried to make a 4x7x4 cone before, and I couldn’t get it past an Octagonal Pyramid.
You couldn’t get it past that because you got union unsolvable errors, or what?
CSG is supposed to be the solution to more primitives. However, if CSG is failing to solve things, perhaps the best solution would be to improve the reliability of it.
Oops, the last edit I did made it no longer implied it was an unsolvable answer. 
They should just allow converting meshparts to physical primitives (assuming theres no holes or other weirdness). Might take some effort, but once thats done, no more problems (unless they want to specifically optimize a particular shape for physics).
Going to bump this as cones would be great for my next (possible) build.