Score before building to ensure a perfect fit. Score tabs and corners There's no better assurance that all your pieces will fit just right than scoring all the tabs and corners. A letter opener works well for this purpose. You'll also find a number of dull-edged tools well suited for this in graphic shops It's easier to score on the printed side of a piece, using the scoring mark (here shown in red) as a guide. Run your scoring tool along the scoring mark, using a straight rule to insure a perfect scoring line. Be sure you're scoring right in the middle of the scoring mark. Repeat the scoring action a couple of times. This will allow you to fold your pieces with ease. Please not that some pieces, like the 3 of the figures, will be scored on the right side but turned towards the back. (Of course, you're free to score these pieces on the wrong side, but you'll have to transfer the scoring marks to the wrong side first.)