As are most of my Instructables, this is a general reference guide and not a in depth tutorial. You will need some prior knowledge to complete this project.

The official name of the toy is called the Archimedes Trammel. It was created in order to turn linear motion into an circular motion (much like a engine piston).

The theory of operation behind it can be read here:

https://en.wikipedia.org/wiki/Trammel_of_Archimed...

Prerequisites:

Bandsaw for cutting metal
CNC or a manual mill
General metalworking know-how
A well-ventilated place to melt aluminum or aluminum stock
Knowing how to use Solidworks or another CAD program is really helpful for creating a model and setting dimensions for all the parts of the trammel.

Step 1: Smelting Aluminum

The first step is to either make a smelter for aluminum or start with regular aluminum bar stock. If you decide to make the toy out of bar stock you can skip this step.

I am sure there are plenty of instructables on how to melt aluminum so I will let you find an appropriate one for your own needs. I suggest making the crucible out of an old fire extinguisher. The first crucible was made out of an empty propane container but the steel was too thin, and the aluminum spilled out during our first melt.

Melt a bunch of aluminum scrap and form a bar that is large enough to house your toy. Make sure to get rid of all the slag before pouring, or pour through a steel mesh.

Once the bar solidifies and cools pop it out of its mould.

Step 2: Sketch

I dont have much instructions for this step, but I suggest using a 3D graphics designer such as Solidworks to create a model of the final product. There are a few web-based CAD programs that are free to use and will probably be more than good enough to use.

Step 3: Milling

First I used a bandsaw to cut one of the bars into a rough square. I checked to make sure the aluminum didnt have any bubbles or slag.
Then, using a regular end-mill I created all 6 sides of the rectangular prism, leaving some of the natural surface of the bar so you could see it was smelted.
I also but the 2 grooves with a regular end-mill and then went through them with a key seat cutter to make the sliding notches.
After this I created the two shuttles and the handle to make up the sliding mechanism.
I turned a thin piece of aluminum in a lath to make a 1/4 inch rod. I polished it and then cut it into 3 lengths.
I then tapped two of the rods on both ends and one of them on one end.
I drilled holes in the shuttles and the handle, tapping the out-most hole on the handle and on the two shuttles.
lastly I creating two small aluminum disks and tapped them to create two small nuts.
After assembling the toy I polished all the machined edges.