Introduction: 2018 Marble Launcher

Supplies and Measurements:

  • 2'x2' - 3/4" BC plywood
  • 2"x6" - 4'
  • 1"x4" - 2'
  • 2- 1/2" wood screws
  • 1 - 2 3/4 carriage bolt - 5/16"diameter
  • 14- washers, 5/16"diameter
  • 1- wing nut 5/16" diameter
  • 1- nut 5/16"diameter
  • 1- 3" box hinge and screws
  • 2- adjustable slide brackets
  • 1- piece of 3/4" schedule 40 PVC
  • 2' 3/4"PVC brackets- screws
  • 4- #6 eyelet hooks
  • 2- extension springs
  • 16" piece of 3/4" dow rod
  • wood glue super glue
  • small wood screws
  • 14- #6 washers


  • miter box
  • random oscillating disc sander
  • tape measure
  • 2-foot straight edge
  • cordless drill
  • various sized drill bits
  • phillips screwdriver
  • electric drimmel

How to build:

1. Cut your plywood into a 50x50cm square.

2. Cut a piece of 3/4" PVC pipe to 12" long.

3. Cut a piece of 3/4" dowel rod to 11 inches long, and another piece to 3" long.

4. Using a 3/4" drill bit, bevel out the 11" dowel rod, then take the other 3" piece of dowel and screw it into the 11" piece as shown in the picture.

5. Cut a piece of 1x4 to 11.5"

6. Drill a metal clamp approximately 1 inch away from each edge of the 1x4. Make sure they are centered.

7. Loosen the clamps, but keep the screws in the wood, then slide the PVC pipe through the clamps, and tighten them back down.

8. Screw an eyelet hook into each side of the handle of the dowel rod.

9. Slip 7 washers onto a small wooden screw. Drill the screw about halfway down into the 1x4, horizontal to the metal bracket. Repeat on the other side.

10. Slide the dowel rod into the PVC pipe. Attach the springs to the eyelet hooks on the dowel rod and to the screws you just screwed in.

11. Cut 4 pieces of 2x6 to 8.5" long. Screw them together to make a square block. Then, center the square block in the center of your plywood and screw it in.

12. Cut another piece of 2x6 into an 8.5x8.5" square. Using a 5/16" drill bit, drill a hole in the top of the square. Then, slide your 5/16" bolt into the hole so that the threads are facing up.

13. Clamp the bolt down by putting on a washer and a wing nut. Attach the square to the top of your block.

14. Cut another piece of 1x4 to 12" long. Attach your new piece of 1x4 to the other piece that is holding your barrel by a 3" box hinge.

15. Drill a 5/16" hole into the center of the bottom 2x4. Unscrew the wing nut and slide the 1x4 onto the square box. Screw the wingnut back on, so that your barrel is not attached to your base.

16. Screw the adjustable slide brackets onto each 1x4 as shown in the picture.

17. Done. You are now an engineer!