This is an expansion of the T Puzzle I submitted last month. For that version, only one side of the puzzle was challenging. This version uses both sides of the base and includes covers to make a complete box. The goal is to fit the four Ts and four Zs into the box and be able to close the covers.

This puzzle design is unique and pretty easy to make. However, if you are not up to it, feel to purchase a smaller (T Puzzle) version from online.

This video show the solution. Yep, it looks simple once you have seen it. However, based on my test subjects, it takes a while to figure out.

Step 1: Tools/Materials:

Tools:

Table Saw
Router / Table
Ruler or Calipers
Pencil
Sander
Wood clamps

Materials:

Wood: 1.5" x 24" x 1/2" thick
Wood: 3.5" x 3.5" x 5/16" thick
Wood: 5.5" x 16" x 1/4" thick
Wood glue
Paint/Stain (optional)

Step 2: T Puzzle

I started with the T Puzzle. Refer to that instructable for the Ts and Base build instructions.

Step 3: Z Build

As with the Ts, I used 1/2" x 1/2" wood for the parts. Cut the red and green blocks to the dimensions shown. You will need 8 and 4 of the red and green blocks, respectively.

Step 4: Glue Together

Using wood clamps, glue the pieces together.

Step 5: Clean Up

Clean up the parts by sanding. Since the base and Zs are made from the same wood and I wanted contrast, I decided to painted the Zs flat black. Note that the previous Ts were stained with a dark finish.

Step 6: Cover 1

I assumed a 1/32" (.031") gap between all covers and mating parts. The overall dimensions for the smaller cover are shown here.

Step 7: Cover 1 Parts

Using the 1/4" thick wood, cut the following pieces. You will need 2 of each of the side pieces.

Step 8: Glue Together

Using wood clamps and glue, attach the sides as shown.

Step 9: Cover 2

Again, a 1/32" gap is assumed for the fit. This cover also includes optional finger grabs.

Step 10: Cover 2 Parts

Using the 1/4" thick wood, cut the following pieces. You will need 2 of each of the side pieces. For the orange sides, you can cut the finger hole at this level or cut one wide piece and drill a hole in the center. Next run it across a table saw to get the two sides. See Step 10 for more details on this process.

Step 11: Glue Together

As with the smaller cover, use wood clamps and glue to attach the sides.

Step 12: Base

The previous base was used for this project. This picture shows the dimensions for both sides.

Step 13: Z Solution

These pictures show the solution. You might have noticed that the dimensions show the assembly not fitting into the base. As with the T puzzle, the key to the solution is rotation.

Step 14: Puzzle Presentation

You will give your puzzler the box in a manner as shown with the goal to fit all the Ts & Zs into the box. The video is the easiest way to understand the solution.