I had some steel fender washers (inner diameter 0.25", outer diameter 1.25") and wanted to use them as weights for sewing patterns, so I whipped up this design in Fusion360 to make a little holder for them. Each holder fits 4 of washers I have. Be warned: It's a tight fit and you're unlikely to get your washers back without destroying the print.

I designed this to be printed at 0.2mm layer height and 0.5mm extrusion width.