I've made some objective aperture funnels, to stop down the aperture.
3D printing, the design is customizable with OpenSCAD so to fit any different model of Yours estimated objective. (Apart from Plan!)
They seem to work ok, with some care they can get centered decently; sure with a lathe they may be manufactured with better accuracy, but need more time and skills (and a lathe). So, 3D print, not the top but effective. The 0.5mm pitch threads for inner objective barrels, work like a charm. Ask an amateur machinist to cut a 0.5mm thread!
I'm playing now with the central stop, to get "luminance contrast/reverse darkfield" or other gizmos.
Published photos and 3D model(s) for now on Prusa: https://www.prusaprinters.org/prints/87 ... lmost-any-
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