The DAS around the roof eaves helps to smooth out any gaps and will make tiling easier.
The following two images show how I create 'hills and troughs' the natural undulations of a traditionally built roof. I build up layers of torn paper, one over the other and glued in place with more uPVA glue until I have a subtle rippling. Try not to be too heavy handed with this, I have found that subtlety is the key.
For more details of the LAF Built Something Contest go to this link.
More daily updates to follow.