Now it is very easy to make more wheels! Duplicate layer (Ctrl-J), move, rotate, repeat!
For some wheel layers, change layer color from grey to gold.
Instead of plain rectangles, you can use Pen tool to create nice curved shapes and use them in your wheel designs.
We need more metallic mechanisms. In new layer, use Pen tool to create shapes of these mechanisms....
...then apply the same layer effects.
Then, set this blurred layer Opacity to 50%. Already looks mysterious!
Then in new layer, create even more shapes! And apply the same layer effects.
But that's not all! Merge all layers again (Ctrl-Shift-E), then duplicate layer (Ctrl-J) and set its blend mode to Multiply and Opacity to 80%. Perfect!