Irrational Number Line Games, LLC
CD based terrain is a good stock in trade make-it-yourself item.
I like things you can use in multiple forces. It's even better when a piece works for multiple scales. Giants are like that. A 6" tall guy could be a giant for 28mm, a titan for 15mm, and a kaiju for 6mm. The same goes for hills. Depending on your scale, a give mound could be a hill, a knoll, a mountain, etc.
So we are going to combine both. I am going to embed leftover bones from my skeletal dragon project into some CD based hills.
The core of the hills is some scrap paper and plastic wrap. No sense in using clay for the whole thing. Also, this makes them a good bit lighter to carry.
Now the clay, and just push the bones in.
Once the clay is dry (using Crayola air dry clay), I will paint them up with my 1/1/1 mix of brown paint, wood glue, and sand. This gives me a nice dirt texture. I will sprinkle some grass flock on top, so it dries into the glue, then a little drybrush for color variation and a matte sealant coat.
Here's a single leg bone as a ridge. Uncle Jed is making sure Cousin Cletus was seeing real things and not just seeing things.
The single grey bone is subtle and could be just a rock formation or an indicator of "other things".
The ribcage is more obviously a set of bones. It works really well with the 28mm scifi guys to indicate a much larger species. Even though this was a rat ribcage, it really could be a lot of different mammalian or avian type aliens ... or anthromorph lizards and fish.
The skull is midway between. You can see the eye socket and animal skull shape. But it is not too far off from natural rock formations.
And this pic shows the same size hill as with the above 28mm figures in the context of a team of 15mm aliens.