Buy four casters, pick over your scrap pile, and find a few wood screws. With those supplies in hand, you can save yourself a lot of backbreaking labor moving large objects around your workshop.
A simple dolly is really just a platform on which cabinets, dressers, or other workpieces can be set. They can be moved from one area to another to be worked on (or simply gotten out of the way).
For details on putting together a workshop dolly, watch the following video: