Here are some skids I made from 6061-T6 aluminum (finished ones next to rejects). You don't have to make them as fancy as these. You could take some aluminum bar stock of the right thickness and cut to the correct length, smooth the edges and then drill some holes for screws. I used 6061 because it is strong yet easy to cut/drill, 7075 aluminum is twice as strong if you want something really tough but still light.
