Sand casting technique has been used for roughly 3000 plus years. It is a what you see is what you get style of casting. We use pattern boards for replication and to reduce cost. When that isn’t feasible we use what we call free-style. where we take an item and use that as a pattern. This does not hurt the item and is returned to the owner along with the reproduction part.
Many people have expected a sand cast item to come out looking like a machined part. Well it’s not how it works you must oversize a pattern to machine it down. But this actually saves time over takeing a block of metal and machineing from scratch.
You can sometimes expect small or real minor flaws, with sand casting.