Going back a couple of replies, don't forget when you design a part you should be thinking about how it should be made if it were 3D printed, not as if it were a machined part. The way you design it is almost always different. You want to be optimising the properties of the material and how it's made. Obviously, those parts were used to get an idea of cost, but never make the mistake of trying to replicate machined parts in a 3D printer - it's a missed opportunity to do the things you can't do when you start with a solid block!
Going back a couple of replies, don't forget when you design a part you should be thinking about how it should be made if it were 3D printed, not as if it were a machined part. The way you design it is almost always different. You want to be optimising the properties of the material and how it's made. Obviously, those parts were used to get an idea of cost, but never make the mistake of trying to replicate machined parts in a 3D printer - it's a missed opportunity to do the things you can't do when you start with a solid block!