Ikea Samla wheel's base

I need to put Ikea samla box on wheels for better usage when it is under a desk, I decided to design a plate to fix under the box and where fixing the wheel's plate.

I'm using them on a 65L samla box.

I used this wheels
https://www.banggood.com/it/Machifit-CC-2004-4pcs-1-Inch-White-PP-Plastic-Furniture-Foot-Wheel-Flat-Moving-Universal-Wheels-p-1335880.html?p=Y7031016841458201712