How to make a simple table dolly?

I want a platform with wheels.. that's it. What EXACTLY (I emphasize "exactly" to avoid a sarcastic answer) do I need to make it? How can make it (go over the steps)? And how much would this cost me. Again, I want a platform with wheels, which I can put a light-weight DSLR (Canon T2i) on. No tripod head mount; no flexibility to turn the dolly. I have no knowledge (not even common knowledge) on engineering/making things.