On Sep 7, 7:02*am, Ed Clarke wrote:
I need to make a very simple box with inside dimensions of 12 inches by
18 inches by 3 inches high. *The problem is that this will contain a
granite surface plate that weighs eighty-five pounds.

Instead of lifting the box, I'd think in terms of putting two handles
on each side, for a two-man lift. Easiest would be two
2x2 oak sticks, protruding beyond the 12" dimension to
let you grab 'em. Use 2" x 2" x 21.5" sticks, set the box
atop 'em and glue/screw together. Then put the stone in the box.
The top is a dust cover, basically...

How to gently lower the stone into the box:
Drill drain holes in the bottom
Fill the box with ice
Set the stone on the ice
... take a long lunch break.