Screw & Nut Reference for Small Standard Sizes
My first original published thing!
Pay attention to the instructions tab.
This thing is designed hold a nut and machine screw for #2-56, #4-40, #6-32, #8-32, #10-32 (fine thread #10) and 1/4"-20 as those are the most common standard sizes of small fasteners, and I blindly hate metric. Metric fasteners are also much more expensive than standard in the USA, often a couple of times the cost. #10-24 was omitted because I don't use it, and #12 was skipped because at that point you should be going up to the far cheaper and more widely available 1/4" coarse-thread hardware.
The picture included is a roughout with el-cheapo Chinese ABS at .4mm resolution. It's still perfectly functional, but this can obviously be made quite prettier with better filament and resolution.