I used $ store Crazy glue to fix my 15 inch square after I broke it. I put a long strip of clear tape on the bottom after matching the 2 pieces back up, make extra sure to get the edge perfect. I used the tape as a hinge at the table edge and ran a bead of the crazy glue along the crack. I quickly put the ruler back up on the table and held the ruler down and together for a bit. I left it overnight to dry and it is still going strong a year later. I left the clear tape on the bottom because it doesn't interfer with seeing through the ruler and the glue is stuck to it also.