tape (any kind)
3 metal eye hooks with anchors (you will need a power drill to make the holes for them)
paint and paintbrush
1. Drill a small hole into anywhere along the side of each tuna can.
2. Screw a metal eye hook into each hole, making sure to insert it into the anchor on the other side of the hole.
3. Paint each tuna can with acrylic or tempera paint.
4. Line up all three tuna cans so that the eye hooks are parallel. Tape them together where they meet.
5. Attach to wall with thumbtacks, nails, picture hangers, et c.
6. Hang your keys on it. :)