I have not filled my ballast box yet, but plan to in the spring. The thing is a it of a pain to move out of the way if need be as it is let alone filled. Has anyone added heavy duty steel casters to the bottom of the box to allow it to be rolled on the shop floor without having to hook it to the 3 point. I am looking at 4 x 250# casters. I do try to park it out of the way when not in use but something always comes up.