In past years I lashed plastic cat litter containers filled with sand in place, but these would slide, and sometimes break open. This year I still used the cat litter containers, but built a wooden base to keep the containers stationary. It worked so well, I thought it was worthy of becoming my first Instructable.
Step 1: Get Stuff
2x4s (at least 20 feet worth)
three plastic cat litter containers with tight-fitting lids
enough small rocks (1" to 1-1/2") to fill the containers
Surform or other sander