Hi SA - If you land the columns on top of the cars how do you screw to the cars? Do not use foaming adhesive. Its really strong but will expand for some time and can move things around I have found. I always have high Z machines with around 300mm under the gantry. Thats because I do boxes and moulds that are tall. If you can get gal steel in 1.6mm go with that for your laminates. As you say cheaper then Al if you can cut it easily and its stiffer. All your concept sketches are fine the devil is in the detail. Peter