Small parts sorting tray, magnetic stackable

I need to sort small parts for my projects.  I want to make some trays on-demand and also stackable so they can be easily stored when I finish my project.  So I made this sorting tray for my needs.

This small parts sorting tray is 150x100x6mm.  It is very thin yet still enough space for small parts up to 5 or 10mm high, it can be used as a try, or as a lid to another tray.  You can also stack multiple trays together.  Using the magnetic system, they are highly stackable!

There are two types of parts unit: 28x31, and 28x63, they can fit parts with different length.

Typical usage:

1. Put small parts in the tray.
2. Put small parts in the tray, and cover by another tray, so small parts won't fallout. (works for parts hight <5mm)
3. Put small parts in the tray, and turn another tray upside down as a cover.  (works for parts hight <10mm)
4. Stack trays together as many as you want.

It is against intuitaion that the tray can be stacked in both ways, this is because the magnet is embedded in an interleaving pattern.  No matter how you orient the tray, they can be stack together by magnetic force.

Magnetic: four 5x4mm, I don't have 5x4mm magnet so I use eight 5x2mm instead.

Print: PLA with 0.2mm layer hight, add a pause at 5.0mm height, then install the magnetic following the image.  Note all trays needs to have the same magnetic pattern or they won't stack.  Test your magnetic orientation before resume printing!