Here's how to save your aching back next time you have to move something heavy in the workshop. A workshop dolly is really just a platform on casters. You don't need extra craftsmanship, just simple two-by-fours, wood screws, and four heavy-duty casters. For a dolly that's good and strong, use lap joints at the corners, with the casters right below. That will help lighten your load.
For more on workshops, consider:
How To: Build a Sawhorse
Planning Your Woodworking Shop
DIY Workbenches: 5 You Can Build in a Weekend