I designed this for my 3D filament storage: https://oscarliang.com/keep-3d-filament-dry/
But of course you can use it for anything you see fit.
It's big enough to hold around 300g of silica gel beads. The holes are 1.7mm wide, so should be good for 2mm-5mm beads (or larger).
You will need 4x M3 nuts to insert at each corner, and 4x 8mm (or longer) M3 bolts for securing the lid.