NTS&B Fall vertical wall creation second method

A fellow club member that professional builds layouts showed us how he quickly creates mountains.   He glues layers of Styrofoam together, then uses a wood drill bit in his electric drill, and knocks out chunks of foam using the side of the bit.  Here is my modified attempt.

I started with 2 inch pink Styrofoam used vertically.

Then I used wood bit at an angle to carve out chunks of foam.  

A vacuum cleaner is a must for cleaning up loose foam.

Here is the painted carved wall face.

Then I added lichen and ground foam,

i performed the same basic steps on some 3/4 inch foam,

 but had to be careful to not go through the foam.

Here is the completed pass with both sides installed.