This simple wooden lock puzzle will challenge your mind. You are given three wooden blocks. The goal is to assemble them in the cross pattern shown.

I started this as an "I made it" project but since I changed the size and building techniques, I thought I would include detailed build instructions. The original versions are shown here and here. Also, I think this was pretty easy to build. However, it you are not up to it, similar version can be purchased from online.

This video gives away the solution. Skip it and don't go past Step 10 if you would like to try to figure it out from the drawings.

Step 1: Tools/Materials

Tools:

Table Saw
Router
3/8" Roundover Router Bit
3/4" Straight Router Bit
Band Saw
Pencil
Calipers
Sander

Materials:

1x4 by 20" Long
Paint/Stain (optional)

Step 2: Drawings

This is the top level drawing. Detailed part drawings are included for the three pieces.

Step 3: Blocks

I used a scrap piece of 1x4 cedar for the blocks. I started by cutting it down to the desired width (2.25"). Note that I cut a board long enough to make six pieces (vs. the required three). Knowing myself, the extras come in handy when I mess up, which is quite common.

Step 4: Rounded Edges

I used a 3/8" roundover bit and routed the board from both sides. This was done for both ends.

Step 5: Cut Blocks

I set the table saw to 6" and sliced the board down. Edit - This is the wrong way to make cuts. Although easy, you should not use the table saw rip fence as a guide for cutting wood to length. The wood can become trapped between the fence and the saw blade and pose a kickback hazard.