Serious about making books? We now have 12x15 book board sheets at the store  . . . #18 is $3.15 per sheet and #25 is $2.35 per sheet. You can go to a professional printing company to cut it down to a smaller size or use a Carl cutter for the most precise cut; otherwise, you can always use your box-cutting or X-Acto knife and run it back and forth several times.