Portable workbench - table on trestles

This "insertable" "temporary" welding bench straddles between two trestles. Any two trestles, anywhere, etc. Given there is a shortage of bench space, with providing access for big structures and components.

Construction seen - the underside in view

With careful handling, one person can slide it into place. It's very stiff - vastly stiffer than a steel plate without stiffeners. There was a shortage of "stock" 60mmx6mm flat, so I had to improvise with what I could find in the scrap - various offcuts. Note the far diagonal has a "splice" to make the length. Still just fine...

Diagonal stiffeners are much more effective that spaced transverse stiffeners.
Engineering reason is understood - explanation complicated.

(R. Smith, 16Mar2021)