How is the corner on Azuma Makoto's LEGO bonsai tree done?

Question

I'm looking at doing my own version of Azuma Makoto's bonsai. I know it will probably not be a 100th as good, but I want to try anyway. The first step is obviously building a similar base but I'm having trouble figuring out how he built his. The photos don't make it clear. I've tried just staggering them as they go up but that doesn't give the same effect. Here is an album for more reference.

Answer 1

The two corners of the bonsai tray shown in this image appear to be built differently... I've chosen to do the technique shown on the left.

The best I could do was use various lengths of two-wide bricks and staggered them in a upside-down pyramid shape with 2x2 bricks in the corner.

I was trying to re-create the model from memory, and I forgot to add another row of staggered plates.