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
Step 2: Preparing the card
This is an optional step. I found that with lighter-colored duct tape, you can see the design on the card beneath. If that's the case, put a few strips of electrical tape over it to block it out.
Step 3: Laying down the color
Now take a strip of your colored duct tape and place it over the card. It won't cover the whole card, so line it up with the top. Don't worry if any of it hangs over; we're going to trim it later anyway.
Purple - Saturn
Blue - Mercury
Green - Uranus
Red - part of one of the puzzles (but I won't say which)
Yellow - one you find towards the very end of the game that I won't give out any more details on.
Step 4: Adding the black bottom half
Here's where the rest of the black tape and the ruler come in. Your standard card is 54mm tall. Therefore, you will want to measure 27mm from the top or bottom to find the middle. Make a mark there, then cover the bottom half with electrical tape.