For prototype purposes I would mill the profile of the larger "carrier arms" from a 2.5" thick piece of stock ( assuming it would finish at 2." thick) in a vise and then flip the finished part over and mill off the extra stock and take it to finished thickness and any other features on the back side.
From what I can see you have a fairly straight forward set of parts not knowing what the material or tolorence are.
I wish I could work on a project like this were I'm employed. We mostly make machines for the web converting industry (paper making) and they really wouldn't know how to go after something like this in the office so I'll never see this kind of stuff out on the shop floor.
Keep us posted on any progress.