Here is a link for a pretty shard tutorial on making some really nice looking hills. It is really easy and the results look awesome.
Link - Hand Made Hills
We don't have any hills in our terrain pool right now but we do have a few that are about halfway done. This just might inspire me enough to finish em up.
The biggest problem that i have ran into with terrain like this in the past is durability. Since the whole thing is insulation foam it tends to flake of or get little dings in it. This is especially true for store terrain that sees more use than what we keep in the garage.
Does anyone have any tips on a way to make this type of terrain more sturdy? I would love to hear it if you do.