PURPOSE: This tutorial is prepared to achieve the below shown 3D background effect in Photoshop.

PROCEDURE:

Step 01: Take a new document of 720 x 576 pixels with default resolution of 72 pixels, and save the file as '3D BOX BG'.

Step 02:Apply foreground color of your choice as i have chosen green as shown below and black color as background.

Step 03: Goto Filter menu > Render > Clouds

Now, your photoshop image will look like below..

Step 04:Goto Filter menu > pixelate > mosaic.

Change the settings as shown below.

Step 05:Goto Filter menu > Brush Strokes > Crosshatch in that case you need change.

change the settings as shown below.

Step 06: Goto filter menu>stylize>find edges..in this case only we can see only edges.

press ctrl+I (or) goto Image menu>adjustments>Invert..

Step 07:Go to filter menu>blur>radial blur and change amount value to 32 and click (zoom&best opation)

Step 08: go to filter menu>stylize>find edges..

Invert the image (ctrl+I).

This is the final effect.