Customizable Card Boxes and Lids

**This is still very much a work in progress; feedback is really welcome.**

This Customizer lets you create cool boxes and lids for the cards that come in your favorite tabletop games. The boxes use a lock-and-key mechanism that lets you securely stack boxes on top of each other, keeping everything neat and secure. The boxes will work with virtually any card size or deck thickness. You can add labels to the boxes and lids so everyone knows what goes where. And everything prints easily with no support needed.

**Important:** This customizer supports the creation of up to five card boxes in one Thing (for different types of cards in one game). Due to Customizer limitations, your created Thing will *always* have five box files and a lid file. If you chose to create fewer than five card boxes, then some of those box files won't be needed, and you can (and should) delete them from your customized Thing before publishing it. You'll know these files because their thumbnails will say "You