You have probably already glued the laminate, but one method is to sandwich a 1/4 thick mdf (with hole as large or slightly larger diameter than trackball hole) between laminate and mount plate to use as spacer for the bit bearing gap when cutting. If you have already glued and/or drilled all your other holes, another method is to do a rough freehand cut, leaving excess laminate, then trim with a sharp narrow blade, using only downward stroke into laminate toward and along the curvature of the mount plate, which may take a bit of go rounds to get clean edge. Just a general laminate tip; you can use a black permanent marker to help mask any upturned or exposed edges to match the trackball plastic.