First, clear the Final Stage and save it to memory card. (If you do not have a card, you will lose this when you turn the system off.) Now go into Options and select Game Mode, Choose SYSTEM and press RIGHT to turn Original Mode on. Exit Options and select the 1P game. You can now make your own puzzles!
Note: You cannot view the rules, get an IQ, or play a 2P game in Original Mode, but you can always switch it back to Normal mode by pressing LEFT at the game mode option.