If I were to make one all it would take is some ply wood, four screws and four wheel bearings from skates or a skateboard.

Plywood...... 1 piece cut 3" X 12" and two pieces cut 3" by 3".

Screw and/ or glue the small pieces to the long piece at the two ends. Cut a notch on the top of the 3x3 pieces and screw the bearings so that they portrude into the notch and the arrow can spin on them.