The really time-consuming bit is comparing similar screws or bolts. They all look the same. Come to think of it, IF I had a quick way to identify them (e.g. a

The really time-consuming bit is comparing similar screws or bolts. They all look the same. Come to think of it, IF I had a quick way to identify them (e.g. a machine vision system), I could keep the organized by keeping DISsimilar screws together. Sheldon Brown had a system where he kept 5mm/10mm/15mm/... in one color, 6mm/11mm/16mm/etc. in another. Color + very rough size was good enough to find the right tool: https://sheldonbrown.com/colorcode.html https://sheldonbrown.com/colorcode.html Something similar might work for fasteners. Binning the would help a lot. If I could identify them in the first place. For which I need some kind of open-source machine vision system or something. To answer your question: I have screws, bolts, and nuts left over from installing things, from fixing devices (e.g. laptops), etc. all sorts of place. This morning, I disassembled a clock which broke to see if I could fix it. I tend to reuse parts when building things. The little plastic screws from the clock are perfectly usable. I can drill a hole in a piece of plastic, and screw them in. In this case, I don't need precision. For something like a laptop, I do. One of the bolts fell out of my laptop, and I'd love to be able to quickly find a replacement.