[Cob] Dome Roof + Cob Planter ?

[ddraig]

Hello,

I'm just reading The Hand Sculpted House, and since its becoming Spring 
I thought I would try and build a cob planter as my first structure, 
then perhaps later on into a greenhouse. I was curious has anyone done 
this, if so how successful was it?

I also had a question about domed rooves. How difficult is it to make a 
domed roof for a round cob house?

Thanks,
Owen (aka Ddraig)