stackable trays with bins

It's one of my first 3D designs!
I made this because i need to organize my electrical components. They are stackable and the inner space is organised in a 3x3 grid.
any feedback on design / functionaility is welcome :)

Other sizes
half height: https://www.thingiverse.com/thing:2828592

Custom bins and trays
headers: https://www.thingiverse.com/thing:2828457

Original sizes
Here are the original sizes in which I designed this. If you keep the scaling the same you can increase or decrease the sizes easily.
On the tray holder set the scale to 1.333 (or increase with 33.33%) for a 4x4 grid tray.
Tray
Total: 150mm x 150mm x 27.5mm
Walls: 1.5mm
Inner space: 147mm x 147mm x 24mm

1 grid box
Total: 48.5mm x 48.5mm x 22mm
Walls: 1.5mm
Inner space: 45.5mm x 45.5mm x 20.5mm

2 grid box
Total: 48.5mm x 97mm x 22mm
Walls: 1.5mm
Inner space: 45.5mm x 94mm x 20