truing the top and bottom of a four sided box
hi, my name is john and i am new at this so i was hoping someone has a simple solution for truing up the top or bottom of a box... i am making a wooden box to bury my wife's dying cat in ( 20X15X10 ) and though it is a perfect rectangle the bottom and top are not flat now that it is glued up, so the box rocks from canter corner to corner. i could use my sanding bar but that would only get it flat, it then might not be level to the top of the box???
i have most wood working tools, table saw, lift router etc and i would not mind buying some kind of jig or making one if need be.