Need Some Advice

I have been making parts from acetal using a vertical mill that slide into slots for this part.

Machining this part is slow and ugly.  How hard would it be to make a mold and cast fiberglass or some other tough material to match these ends?  They don't have to be hollow, and if you know of something that could roughly approximate this, that would be fine.

Those sort of trinngles are 1.0005" wide, .765" high on the narrow side, and 4" long.  There is .485" between them.  Something welded of aluminum?  Two 3/4"x1" rectangles welded at the base. I have afriend with a welder.  I'll call him tomorrow.

I am thinking some off-the-shelf aluminum extrusion probably looks like this at the end.  Perhaps something I can cut to match.