There is also a material called microlam, which is a high grade, thick, sort of plywood used for beams. I found a piece some years ago and carved a few bowls out of it, all was well except wood is different than stone or metal in that it can catch fire when you are not paying attention.
On the discussion of removing material that is not there, the approach is not one of disliking 3d printing. This is kind of like saying that, if I am going to build a machine, I am only going to use wrenches, and no screwdrivers; of course that would be foolish, both wrenches and screwdrivers are tools, and you use one or the other depending on what you need to do. Same for 3d printing, or subtractive machining, or material forming without addingn or subtracting. different tools and techniques for different purposes and results.
On the ‘way of thinking’, removing the material that isn;t there, many sculptors and artists will do what is called a study piece on a complicated design. You do a small piece, work out the 'tool paths" (which can be a mill cutter, a hammer and chisel, the angle of a grinding wheel, the angle of the blacksmith anvil relative to the work and your hand held hammer, the angle of the molten glass bead on the end of a blow tube, etc) and then go on to create the real piece. During the process of doing a ‘study piece’, you learn about the material you need to remove, and from there you teach yourself about the shape you are trying to create.
So, to the calculation problem at hand, a) You can try modeling the material you are trying to remove; b) you can model then actual surface you want to create, with zero thickness c) you can take surface from B and add thickness, radius the edges,
Also, you might want to grab yourself a piece of wood and a file, or clay, and have a try at forming the approximate shape by hand. You will create an ugly study piece indeed. try it again, ti will be slightly better, still ugly. try a third time, and it may still look pretty bad. So what, in the process of the hand forming you will teach yourself about the shape you are creating, and wanting to model.