Never done it, but I saw a presentation once at bonsai club meeting, so I'm far from being an expert on the subject.

I think Kokedama soil (aka Keto or "muck") is supposed to be a very dense clay like soil that will hold its shape when formed. Bonsai soil or 5-1-1 would be way too loose for that.

I think it was potting mix and sphagnum moss and perhaps a little (optional) soft akadama, which is a very water retentive baked mineralized clay, and is hard to find as most bonsai practitioners use the hard baked akadama. Again, don't hold me to that.

Damn, Now you got me thinking!

I have some nice marble/granite slabs and there is some nice delicate grass clumps that are growing down by the creek. They would make nice gifts and table centerpieces for the holidays!

I suppose I’m just going to give it a go and see how it pans out. The one I purchased from a local farmers market has held up beautifully and my grandmother fell in love with it and stole it! I agree they make nice gifts! I was thinking about making some along with some polymer clay bowls for them to sit in or they can be hung.