I recapped and repaired a Fisher 500 mono receiver that I purchased a few years ago. Unfortunately, the knobs were missing. I watched eBay for several years for a replacement set, with no luck except for one inner and one outer knob, so I decided to try having them 3d printed. I used a free CAD program, Fusion 360, to make up the drawings from a single inner and outer knob that I did have, and sent the files to Shapeways, a 3d printing service in New York. Cost to print the parts was about 40 dollars, plus the brass inserts, which are small freeze plugs. The knobs are made from fused sintered nylon (polyamide) and seem very strong. The surface finish of the raw parts was rough, about like 400 grit sandpaper, and the only color I could get was white. Other than the slightly rough texture, the parts looked pretty good- none of the layering lines that are typical for some 3d processes. I filled the surfaces with thinned Tamiya modeling putty, and sanded them smooth. The filling and sanding was the hard part- I spent a few hours of fiddly sanding trying to get them right. I then painted them with an airbrush with acrylic paint, followed by a coat of clear acrylic. The knobs are secured with set screws. By the time I was done, I had about 80 dollars into them, plus quite a few hours of my time. Didn't quite get the color right, but pretty close.
Ganged knob (raw)
Finished 3d printed knob
Original knob is on the right.
Ganged knob (raw)
Finished 3d printed knob
Original knob is on the right.
