I thought this picture looked 3D and commented on it at the time.
The colors involved are the same as in yours.
It's common practice for sign writers to use strong contrasting colors to achieve a gaudy but eye-catching effect for low cost.
If you want to experiment with this you could open a new blank image in PS and fill it with a strong color - blue, red, orange etc. Then, using the color picker, try and predict which color will produce the strongest clash (and thereby 3D effect) and then paint it onto the background.
[use vivid shades. --------- orange on blue --------- green on red] |