I used to use Ikea Lack tables, but I had closet shelving as a bottom to the cage, and it's much stiffer than grids.
However, you can make a grid support very sturdy, and it will easily support a large cage AND keep your dog out if you keep it covered. I'd recommend closet shelving for a lid, though, as that's safer than a grid lid.
Look through the Photo galleries for pictures. If you build a grid support, use the connectors, snap the wires in place with pliers, zip-tie all the corners with at least medium strength zip-ties, and use a dab of hot glue at all the joints. It will support a baby elephant.
