I'm working on a project that may well end up having a case made of
>fiberglass. As I'm working on a 3D model that will use mostly to make
>pretty PDFs for my fiberglass guy and my customer, It occurs to me that I
>could just make a 3D model of a mold and send it to a machine shop. >
>A 1.25 x 12 x 48 inch piece of 6061 costs $430 from Online Metals. Is
>that pretty much what I would expect to pay for materials from a machine
>shop? Is there any material that's significantly cheaper, that can be
>tossed into a CNC mill and made into something mold like, and then hand-
>polished to a high shine?
====================== As you already have the wireframe/3d drawing you might consider getting the mold/plug 3d printed. I don't know the details, but from the web it appears this is becoming increasingly common.
Given the size you most likely would print in several sections and glue into the complete mold/plug.
Some URLs of interest
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