In simplest terms, I have a cube. I also have a shape that is fairly complex and cylindrical.

I want this cylindrical shape to be at an angle, say 20 degrees. Then I want to cut down in the cube from one surface to the item.

This would have a half cylinder bottom with straight sides to the top.

So far I can subtract the cylinder shape from the cube and projected the cylinder to a plane at 20 degrees. I hoped to extrude (or subtract) into the cube down to the widest radius of the cylinder to slice that out. I can’t figure out how to extrude non-normal to the plane.

Second try was to copy the shape up and try to figure out how to make it a 3d shape that I can subtract, but I can’t figure out how to join two sketches together to make a 3d shape.

Anyone have a solution for this?