AusBonsai

I am putting together a tray scene using a neat little concrete mountain I picked up from Bonsai Art in Sydney.
I have three Hinoki Cypress for the mountain, and I would very much like to incorporate a stand of bamboo into the scene. Ideally it would need to be happy at around two to three inches tall, and in very shallow soil. Does anyone have any suggestions?
Not Mondo grass...

I have 2 different dwarf bamboo type plants. Both are a little taller than your 2-3 inches but are the smallest I know of.
1. Pleioblastus viridistriatus - Variegated Golden Pygmy Bamboo. As the name suggests it has green and gold striped leaves. Normally around 70cm tall but with limited root run it stops at about 10cm tall.
2. Variegated paspalum (I think?) Silver and green striped leaves and softer stems as it is not really a bamboo. Tends to die down in winter. Normally about 50cm tall but in a small pot seems to stop at about 15-20cm.

Both of these spread by underground stems and make a clump quite quickly.

Nandina?

Photos of the 2 I have suggested above.

This one should be about the right size. The silver one is a bit taller than I thought it was - 20-30cm - so might be a bit big for your plan.

Both very cute Shibui.

The old dwarf mondo grass maybe worth considering?

Great suggestions, thanks peeps!
The Pleioblastus Viridistri looks just right, and I recon I can find room for some Nandina too.

After looking around a few places, I found some Pogonatherum paniceum, Baby Panda Bamboo, at Eden Nursery in Lane Cove. It's not a true bamboo, being closer to sugar cane, but it looks just right. Fine stems and small leaves, the scale of the planting I have planned needs it to be as small as possible. I have three clumps, and I'll trim them down to under half the current height over the next day or so. They will form something of a jungle down the left hand side and behind the mountain. There'll be Hinoki Cypress on the rock, and a gravel lake and moss over the rest of the tray. Hoping to put it all together at Ray Nesci's First Sunday muster next month.

Subscribed. Good luck and look forward to seeing the results.