If it needs any amount of strength you'll want to find someone with a lathe. BSP tells me it may be tapered(?) so find someone with a taper attachment. Even as a hobbyist I could probably make one of those on my lathe faster than drawing it and printing it on my 3d printer.

Print a mold, cast it in wax, put that in casting sand, then do a lost-wax casting in aluminum or something more exotic if necessary and you're able?

A 3D printed plastic part could be fine depending on the application. Certainly worth considering/testing. Printing it flat on the bed (with a small flat side) so layers are lengthwise may work.