Corner Guides by We R Memory Keepers helps you think outside--and inside--the box! Use these clever, convenient guides to make the perfect sizes of boxes, book covers, dioramas, and more! The guides hold onto the corners of your projects tightly while your adhesive sets, giving you the perfect shape every time. The Corner Guides work well with 3, 2, 1.5, and 1 mm wide chipboard pieces, and can be used for all sorts of projects for work, school, and crafting.