I've just fired up my first RMH build. (Chuffed to bits)
It's quite small - 8cm × 8cm.
So, I made a P-channel (using an old stove shovel) but it was quite a bit too deep and I fumbled the re-cutting of it badly. It was too loose. Grrr.
I gave up on it and settled down to lunch.
In an earlier post I asked some growies "what's the best wood for burning in a rocket mass heater" - and a great growie called Peter helped me realise my bamboo is far from useless but perfect.
Fast growing.usefull for all sorts of other stuff. Makes a fab windbreak and provides enough good food to keep a pet panda.