These are small parts trays. I made them to help when looking through a jumble of small screws or other items.
The idea is the there is a largish flat area to sort through the parts to find the one you actually need.
When you're finished, you can tip the tray and pour the unwanted parts back into their container via the spout.
I hope you find it useful.
Why three? Well I just had three ideas and made them all.
If you want to resize these, just bear in mind the wall thickness of the original is 1.5mm