When making a wooden box often some imprecision is introduced. That’s why the bottom leveling needs to be done. That way when box is put into place it does not swing. Up to now you repaired your design by putting box on some surface and than then trying to send it to make it better, just to find that on other surface it does not stand so well.
Instead of your usual practice, I suggest you my way of leveling a frame/box.
This article is really quite optimistic one: there is a solution for globalistic devastation of farming. We should go in completely different direction...
2.3.2018, Serbian version: 16.12.2017