It can be either. Took me 40 minutes to make, it should only take you 5 or 10.

Step 1: The Flywheel

The second most important part. Make two of these with the exact parts. please note that you have to have the white counterweights matching the opposite wheel on the other side of the shaft.

Step 2: The Crankshaft

This is the most important part, use the exact same parts, no shortcuts.

Step 3: Flywheel Stand.

This will keep the flywheel from rubbing.

Step 4: The Cylinder.

This will keep the piston (long rod) in one position. it can be made of 2 sided connectors, the half discs, and full discs. it must be 16 pieces long and have a hole all the way threw.