First a swatch of 0.010” plastic covered the slot in the base.
I then mixed up some epoxy putty and shoved a dab onto each base.
A drop of water was put on the putty to act as a release agent, covered with a sheet of wax paper, and then rolled out with the handle of a hobby knife.
You want to roll the putty out until you can clearly see the edge of the base all the way around.
Here’s the base with the wax paper pulled off. The excess putty pops off easily and the rest of the residue cleans up easily with a wet paper towel.
Know the pattern of the dry lake bed was cut into the surface with a hobby knife. Try using various size irregular polygons ranging from triangles to hexagons, with quadrilaterals and pentagons dominating.
After the putty cured, the bases were primed with white primer. They desert was then base coated with Delta Ceramcoat Trail Tan. Once that was dry, a wash of Renaissance Ink brown ink mixed 1:4 with water covered the base. The desert was finished with dry brushing of successive layers of Tail Tan and White in ratios of 1:0, 2:1, and finished with 1:1.
Hope you've found some of this usefull!