One of my favorite rulers is a 6x24 "Quilters Rule" because it has nubs on the bottom to keep it from moving. It works great! Press down on this sucker and it ain't going anywhere! Only one problem ... it's made from cheap hard plastic - not lucite - so the edge is all chipped from the rotary cutter.
If he can make this nubby ruler out of a nice non-chip plastic I would be in heaven!!