I had a great day on Sunday helping out 
It was a great day with some good company, good food, and I learned a lot about Cobb too, never having worked with it before, although it's such a simple process, there's not a lot to learn really.
The first stage is to get some earth - with a decent clay content, and fortunately these guys just happened to have soil of just the right consistency to not have to add anything to it (you can add sand apparently if it's too heavy, but this wasn't necessary in this case).
Then it's a matter of adding water and a tiny bit of straw (for a floor) and water and mixing, you basically need these materials:
We did load one in a wheelbarrow and then evolved to the more classic 'feet mixing method'. It actually takes a couple of people around 15 minutes to make up a decent slack-wheelbarrow full of this mix...
However, it's not really too hard work - you just have to able to move your feet up and down and body weight does the mixing!
Then into buckets for transporting into the Tipi to put the Cobb on the floor and level...
And it helps massively if you get the under layer of dirt wet before levelling, it helps with the smoothing process massively.
NB this in itself took a lot of work - there's several barrow loads of relatively fine earth, sifted, on here already!
This took 3 people about 3 hours to do which I think is pretty efficient for amateurs.
It doesn't go all the way to edge as there's another inner layer of insulation to put in the TIPI which will come in further.
Now it's just a matter of letting the floor dry, and this might require keeping it wet I think to slow down the process!
The whole process went really smoothly, 9 people managing sifting, mixing, slapping the Cobb on and levelling, and childcare into the mix too.
I'm sure
