You may need a cardboard harp for a church play or a Halloween costume; whatever the reason, it is quite simple to make a cardboard harp using only cardboard and fishing wire. This is an excellent craft to make with a Sunday school or music class because you can associate it with a lesson as well.
Draw a trapezoid on a piece of cardboard. The trapezoid can vary in size. You can use a flattened cardboard packing box for a larger harp, or a cereal box for a smaller harp. Cut out the trapezoid and lay it so that the longest point is facing your body. Count in about 2 inches from one side and cut straight up and down, cutting off the corner. Do the same thing on the other side.
Make horizontal slits along both short sides of the trapezoid. Each slit should measure about 1 inch from the edge. Do not cut slits in the long, flat sides of the harp.
Carefully make a hole in the harp that is about 2 inches from the edge, and 1 inch past the slit. Cut out the centre of the harp, following the outside lines of the trapezoid.
Find the middle of the fishing wire and slide it through the 1st slot. Pull the wire tight, and pull the other end through the matching slot on the other side of the trapezoid. Tie the 2 ends of the fishing wire together. Repeat this process for the remaining slots, creating the strings of the harp with the fishing wire.
Spray paint the entire harp with gold spray paint. Allow the harp to dry completely.
Use rubber bands instead of fishing wire if you want to actually make noise with the instrument.
If you are working with children, make sure you make the hole in the centre of the harp for them so they don't cut themselves.