This is part of a current project I am doing, I am not great at metal manufactuing processes. Please see attachments (ignore white rubber and screw tight fitting thing).
It is to clamp a material between the upper and lower metal funnel shaped objects.
The material used needs to be very durable, uv resistant, and cannot rust.
How about cast stainless steel?
Are we talking about the thumbscrew clamp thing? I would first look for off the shelf parts. That’s a fairly common kind of component. If you absolutely have to have a custom part, what you do is all going to depend on volume. It’s four unique pieces and it requires hand assembly.
The clamp and thumb handle parts can be cast in aluminum or stainless if you are doing some volume (thousands). Probably investment cast, maybe die cast if you need tens of thousands. The screw part needs to be machined. If cost is an issue, you’ll probably have to do these in Asia to keep the assembly costs down.
For lower volumes, have all of it machined. You’ll have to change the shape of the thumb handle to machine it easily though.