Hi Jon,
My planned project is building a frame that will hold three tool boxes approximately 2 foot long by 1 1/2 foot wide with a total length of 6 ft. Now I need to be able to work from them at a height of about 2 ft but have the built in ability to raise them to a height of approx. 3 1/2 foot. I also have four castors about 4 inches in size, and are set up in pairs with a steel frame, actually they are castors from a hospital bed. I can probably use them in their present form with a little work in setting them up on the legs. But my need to be able to lift the height will not be used very often and the need to do so is simply because I live in a flood area and if I am able to raise the bench with the tool box to a height of 4 foot this will always clear any flood levels, and save me quite a bit if effort. I do have some other benches that I may use a similar lifting idea if this one is successful. Probably you may have some links that can assist me in making some legs with the ability to extend in height with the weight of the tool boxes in place.
Sorry about my story being so long but the need to explain my idea was a bit complicated. Best wishes, Tom