Here are some pictures of kids making foam duct tape weapons. And some kids playing with swords I made.
Step 7: Taping
Add strips of duct tape to the sword. Be careful when applying the tape special around the corners. Take the hobby knife and cut the tape into strips so it will not get wrinkled. When applying a new strip of tape, don't make the overlay more than 1 cm. If you put on to much tape, the weapon gets hard and heavy, making it dangerous to play with.