The following keychains are all manufactured from a steel powder via a 3D printing process and available with the shown platings. (golden, silvery, grey, black and bronze.)
The parts can be purchased in the keychain section of my Shapeways shop HERE.


V8Crankshaft keychain

This is a random V8 crankshaft. Its lenght is about 5.5 cm (2.2 ").

The model includes a feather key groove at the front end and various balancing holes inside the cheeks of the crankshaft for smooth spinning.

Note that the specific part shown in the picture was ordered in matte black steel and sanded in various spots by hand to create a realistic appearance.

On the right is a fairly simple piston rod, shown in polished grey steel.

Its length is approximately 3.5 cm (1.6 ").

Piston Rod keychain
Gear keychain

Shown on the left is a hellical gear in nickel plated steel.

This one is 3.1 cm (1.2 ") in diameter. It has three spokes and a center hole with groove.

Here is another gear, that is called bevel gear with a diameter of 2.9 cm (1.1 "). It has a conical shape and spiral teeth.

Unlike a lot of CAD model pictures that are online, this one is not just a gear with linear teeth, distorted in a twiting way around its axis. Instead this one has properly cut teeth, that are not tiltet in an unrealistic way. The teeth, as well as the cutting profiles, are symmetrical about there center line and all the edges of these cuts are circular arcs that meet in one point on the axis of the gear.

Bevel Gear keychain