As readers know, we have an earthen subfloor that we've been working on top of for a year now. On top of this will go the radiant tube layer, which will be 1.5 inches thick with the tubes running all through it. On top of that will be a .5 inch finish layer. Thus, we have 2 more inches of floor to go, and we have three levels to work with. So, we need steps between them.
We probably could just create clay floor steps, but the potential for damaging the edges and the lack of visual distinction between levels didn't appeal to us, so we started thinking about a wooden sort of 'retaining wall' for the edges of each level.
This would have to be made of a hard wood, as our redwood supply couldn't take the long term traffic abuse. So, I've made some up out of madrone. (the madrone that hung over the driveway)
Here you can see the different pieces that have been roughly planed and lap jointed to go around the curve of the upper level step.