I have had this piece of shaped styrofoam from a Omaha Steaks cooler cover lid. I originally shaped it for 1/72nd models, but it should work for 15mm. It is a hill road with 2 mesas on either sides for observation and artillery. After helping my son work on his Diorama(LINK), I got the itch to finish this piece and try some new techniques while completing this terrain piece.
There are some issues with this piece. The worst is the transition to the base which is to steep, but I do not want to make the base any longer for storage issues, so I'll live for now with the un-realistic transitions.
So next I added some sand that I had around to the area that I decided to be the road. The sand was rather yellow-ish, and I planed to crush it and make it more fine, but in a effort to just move on with the project, I put on the sand when I had a free moment. Using a 50/50 PVA (school white glue) with water I applied the sand. Then I brushed on another 50/50 PVA coar with a brush and aplied more sand and then after everything dried I covered the sand with a another 50/50 pva/water mix, to seal & hold the sand in place. Overall the sand looked good, except the sand was more coarse than I would of liked, but I already know that when I pressed on with the project.
Next I applied Acylic gel with coarse pumice and a 50/50 mix of Craft paints Mustard Yellow and Dark Beige(Jo-Ann72129 Au Natural) to the vertical areas of the terrain to give it the color of a sandy bluff. This worked out well and looked very nice. I then mixed green and Olive Green into the rest of the mixed pumice gel and brushed it onto the areas that were to have grass added to them, so as to be a base for the grass.