I can’t say I’ve ever seen a cnc’d intake but that doesn’t mean it’s not being done. Holding it in position and the multiple twists and turns could get tricky. I have my head v-blocks and probably 5-6 pieces of wood that I throw up on my porting table so I’m not up and down all day. Some guys prefer to stand but with my bad knees I sit for 80% of my manifold work.