Check out your kitchen, you can find a variety of items that can be mandrels. The following list is just a few things that can be used.
Wooden spoon handle
8 oz tomato paste cans, 13 oz soup cans, 28 oz cans. Great for bending hoops for earrings, bracelets and necklace wires.
Bamboo skewers, potato nails and wooden candy sticks, great for making coils.
Mini whisk handle
Next time you are in search of a mandrel, look no farther than your kitchen!