Simple chain

UPDATE 10/02/2015

3D printed it and found that 5mm holes in part2 worked much better, allowing better play. Closed the part3 and made a bigger jig. Now you can snap parts together with a 4mm rod without any glue if you're lucky like me and part3 fits tightly on the rod.

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This is a simple chain design that requires some 4mm rod (any kind as long as you can cut it with a hand saw). You can make it as long as you want, design your own ends, etc.

This design comes with a jig that allows you to ensure rod is exactly the required length (22mm)

Insert and glue the rods you just cut into the partial hole in part3 and assemble the chain as seen in the picture.

Work in progress, didn't print it yet. Some filing and sanding will probably be required.