Engine Dolly - EZ to make
Click the button to see Stephen Peterson's nice design for an inline 6 engine cart.
I made 2 carts for myself and they are really nice. I screwed two 2X4s together instead of using 4X4s. Instead of mounting casters on the cart, I simply rested the finished cart on top of a Harbor Freight 30" X 18" furniture dolly. The dolly is rated for 1000 lbs and the price was less than 4 casters. LINK to HF furniture dolly.
Here are some pictures of my dolly. I kept hitting my ankles on the corners so I trimmed them shorter. They were just hanging over the edge of the dolly anyway.