How to Build Your Own Marble Machine

Use a saw to cut four 30-inch, 24-inch and 18-inch lengths of polystyrene foam tube and one 12-inch length.

Measure the exact center of the foam board and mark it with a pencil. Draw a line from the center to each corner using a yard stick. Mark 1 inch from the corner, then measure 4 inches toward the center and make another mark. Do this twice more, measuring and marking 4 inches from the previous mark. You should have rows of 4 marks at each corner of the foam board moving toward the center mark.

Use a hot glue gun to glue a 30-inch foam tube 1 inch from the edge of each corner on the foam board base. Glue all four of the 24-inch foam tubes to the next mark in, then glue the four 18-inch tubes on the next mark and the 12-inch tube on the center mark.

Measure 1 1/2-inch strips on the foam board. The strips will be used for the chutes the marbles travel down. Choose a corner for the start of your marble machine and measure the distance from the first 30-inch polystyrene tube, glued at that corner, to the second 30-inch tube. Cut a 1 1/2-inch strip of foam board long enough to span the distance between the 2 tubes. Repeat this step from tube to tube in a downward spiral until you reach the center 12-inch tube.

Miter the ends of your chutes so they fit together like the corners of a picture frame. Cut the angle necessary to make the chute turn in the direction you want the marble to go. Use your glue gun to attach the chute to the foam tube. Glue a length of wooden doweling along each edge of the chute for rails that will keep the marbles on the track.

Cut several 1-inch squares of foam board with a razor knife. Glue squares to each corner of each chute for bumpers. Glue two 1-inch squares in a ̶0;V̶1; shape at the end of the last chute to catch the marble.