mook Johnson wrote:
I'm going to be pouring a 3 x 5 slab 8" thick. 2" below ground and 6"
above. It will need to support about 500lbs.

I'll be using quikrete for this. Do you think I'll need rebar for
this small slab?

Eek!

Consider a few 4x4s, a decking of 2x6s, four (maybe six) concrete blocks for
support. You'll need a saw, a tape measure, and some nails. Total time of
construction for one person: 2 hours.

It'll take two hours just to MIX twenty 80-pound bags of concrete.

Also, consider what you'll have to do when the wife says: "It would look
better over there."