Some things I've previously made (and sometimes sent in Christmas cards):
A cardboard, folding Instant Fortress (folds flat until ready to use). Stats/description were on the inside.
A paper Folding Boat: ship battlemap-tile on one side, description and boat battlemap-tile on the other (it can be folded up so just the boat tile is displayed)
Bag with Bag of Tricks paper (2"x 2") tokens: can be drawn randomly and used as battlemat miniatures. Creature image on one side, stats on the other.
Post your thoughts, photos, and construction techniques below! :)
Some things I've previously made (and sometimes sent in Christmas cards):
I'm a huge fan of Fat Dragon Games, but haven't yet made the move to their 3D printer packages.
I've also made a few things from World Works Games, love using the Silhouette Cameo for cutting.
Dave
theDMsCraft on youtube is great for this kind of stuff. https://www.youtube.com/channel/UCF-i5kmuwyV6N3xi5z1TElg
I just want to tell everyone "happy gaming" and actually mean it. Whatever your game is, just have fun with it, it is after all, just a game.