I use a laser level/square to square out my quilt and mark straight lines before I put the binding on. I get an accurate 90 degree on one corner, and then I can measure out to the other two sides and mark my distance. I never get a 'quilt needs to be square and corners 90 degrees critique' at shows anymore.
It is a great tool.

dcrine gave me this idea and I thought someone else might be in need of this idea.

With my quilt top on the design wall, use the level to straighten the raw edge and square it up. Use a long ruler to draw the line , cut and sew on the borders.

my orca quilt didn't have any straight edges for squaring and it was too big to lay flat on a cutting board for squaring. This work great.

Thanks dcrine Cheryl