If you don't already know what 9 Hours, 9 Persons , 9 Doors is, you probably won't be interested in this. Unless of course, it piques your interest and you go buy the DS game and play it until you get all six endings. In which case, good for you. Welcome to our world.
Assuming you've played the game, you'll recall that there are several key cards you find throughout the game which progress the storyline. There are no spoilers here; you get the key cards regardless. If you're thinking about cosplaying someone from 999, these key cards might be a fun little addition to your outfit and/or group. Also, they're easy to make.
Step 1: What You Need
-Old plastic card, like an empty gift card or hotel key card. You probably don't want to use a credit card, but it would be cool if you could get away with it.
-Electrical or other black tape
-Colored duct tape