A recurring frustration when playing Settlers of Catan (a registered trademark. I am in no way affiliated) is that the cardstock pieces tend to warp, especially the outer water pieces that form the frame. This causes some annoyance when playing because the tiles start shifting around. I started a project to solve this problem by laser-cutting a frame to hold the pieces.
I made it at TechShop San Francisco, where I had access to Epilog 60W laser cutters, so parts of this tutorial will be specific to using those, but if you're familiar with a different brand, it should be no problem to translate.
(Thanks to scoochamaroo for inspiring me to make this Instructable)