Jerry, I have used crude ones in the past, including a 6' piece of 2" thick plastic that was 2' wide. I sat down one day and decided that I wanted a decent potting bench. I made the plans in my head and went and bought the lumber. We had to move after I bought the lumber and it was two years before I actually got to build it. I built it last year and it has been a big help. All I need now is to build a matching mixing box. I'm using an old plastic truck toolbox that I cut the top off of.
Sheila, mine is 6' long x 2' deep and the work surface (if I remember correctly) is 30" high to fit my height. As mentioned above, I built it myself. That was one of the woodworking projects that I used to keep me from going stir crazy in this cramped mobile home park. Presently, I'm working on a transport box for my truck. After that, there is a 3x5'x18"deep wood trough and a 4x10x2'deep wood trough. There may be another shallow wooden trough after that, depending on how much lumber is left over.
Scott