Says the guy who hasn't gotten beyond the Pepakura stage himself.
I'm kind of late to the party, but welcome to the Pepakura scene. You've made a few mistakes, but nothing that can't be redone.
1. NEVAR use tape. It may hold up at first, but it will literally be melted by Fiberglass Resin. Not only that, its adhesive properties are less than longlasting.
2. Don't reinforce with cardboard if you're using printer paper. The paper will wrap around the cardboard when resined and end up in a deformed mess.
3. There are three advisable glues to replace tape:
-Hot glue: Hot glue is cheap and easy to find, but causes large amounts of warping, and will burn you if you don't wear medium-thickness gloves.
-Super glue: Superglue is extremely fast, but the most costly of the three and the most annoying (if you get it on your fingers/hands, your skin will stick together).
-Elmer's glue: Elmer's is a medium. It has a slower drying time, but has more time to adjust position. It is pretty cheap and is only needed in extremely small amounts, such as the end of a toothpick.
Good luck on your...stuff!