Magnetic Packout Bin holder

My attempt to make use of spare Packout Bins. I made it so you can use either 2 singe or 1 double length. The magnet holes are 10x5mm. Ive been testing it out and while it works ok with nothing in the bin, an weight will cause it to slide down a smooth metal surface. Not sure if I need to add more magnets, make them larger, or change the depth slightly, But use it as you see fit.