They haven't recieved a topper yet. The owner was supposed to pick up the 1/4 in hardboard for the tops and hasn't - yet. He's been taking on trucking jobs instead. I suspect about field work time he'll get the materials and want it finished. Here is the link to the previous discussion and what I priced metal toppers for over the 2x10's. I felt the 4 - 2x10's made about the right depth for a bench. If I recall about 39 inches wide. I like your idea of using steel. I don't think it would take much thickness with 2x?'s under the steel, 10ga or 1/8 would do it I feel (cause of the expense of heavier steel). Hope this helped -  http://talk.newagtalk.com/forums/thread-view.asp?tid=43194&posts=9&highlight=work%20bench&highlightmode=1#M308559

http://talk.newagtalk.com/forums/thread-view.asp?tid=42626&posts=26&highlight=work%20bench&highlightmode=1#M305005