This is a fun little puzzle that goes by the name of Golf, Nine Hole and, my favorite, Gopher Hole Puzzle. The goal is to fit all six pieces into the box. The possible combinations make it pretty challenging. As for the build, it was fairly easy to make, if you have patience. I used doll pin stands from the craft store for the pegs. The most common version of this puzzle uses wood balls as shown here.

The solution is shown below.

Animated Solution

I've also included STL files (last step) for a 3D printable version for those that are not up to woodworking.

Supplies

Tools:

Table Saw
Drill Press
Forstner Bit, 1.125"
Router Table (optional)
Wood Clamps
Sander
Ruler
Pencil

Materials:

Wood: 1X6 by 4 feet
Doll Pins Stands (x13)
Wood Glue
Danish Oil
Paint

Step 1: Drawings

You will be building these parts.

Step 2: Housing

The housing consists of a bottom and four sides.

Step 3: Top/Bottom

The bottom sets the size of the overall puzzle. I arbitrarily chose 5" x 5". For thickness, I had a scrap piece of cedar that was 3/4" thick so everything is made to that size. You will need to make two of these parts. Note that the top piece will need to be sanded down a bit to fit into the housing.

Step 4: Holes

I marked the centers per the drawing. Next, I used a 1.125" diameter Forstner bit to drill the holes. To prevent breakout, I didn't drill all the way through from one side. As soon as the tip of the bit broke through, I flipped the piece over and drilled from the other side.

Step 5: Chamfers

Since I was worried about lining up the holes in the puzzle, I added a chamfer to each hole using a 45-degree router bit. That chamfer along with the existing chamfer on the doll pin gave me confidence that everything would fit.

Step 6: Sides

Making the sides are straight forward. I used a table saw for these cuts. I'm sure more talented woodworkers could improve these parts with miter cuts or dovetails.

Step 7: Assemble Housing

Attach the sides to the bottom using wood glue and clamps. Sorry for no pictures of the clamping. If it isn't obvious, refer to one of my many other puzzles for pictures.

Step 8: Pins

The pins were purchased from a local craft store but can be purchased online as well. Wood balls, marbles, dowels or other items could be used as alternates. I considered scaling it up even larger and using golf balls for the pins. I would suggest finishing (paint, stain, etc.) the pins before attachment.

Step 9: Part 1

All the piece parts will need to fit into the housing. Note that dimensions shown assume a perfect fit inside the housing which isn't feasible. Therefore, for each part, the overall dimensions will need to be reduced slightly to get a good fit. I took about 1/32" off each side using a sander which worked out pretty well.

As with the bottom, I used the drill press and a 1.125" diameter Forstner Bit to drill the holes. For marking the center hole, I drew an X corner-to-corner. I measured off the outer holes per the drawing. Hole depth was an iterative process. For the doll pins, the depth required to reach the chamfer turned out to be 0.28". Tip: Start with Part 4 and use the through holes as a guide for the remaining parts.

For all the blocks and housing, I finished each with Danish Oil after sanding and wiping them clean.

I painted my pins ahead of time with spray paint. I then glued them to the blocks as shown. I didn't like the center hole from the Forstner bit so I used craft paint to fill in the center hole.