First of all, you need to empty out the box of your device. Take everything out, the manuals, cables, etc.
Make a marking with pencil where you need to make a cut. You would ideally want to make the cut just above the Samsung Galaxy S III text and the USB end just at the bottom of the box.
Use a simple box cutter to cut out the holes according to the sizes you marked in the step above.
Once you are done with it, insert the wires to give them a proper shape. Push the connecting end right where the phone will be placed and the other end through the second hole. The connecting end will be where the phone will balance itself without falling. Make sure you place the cable that way. Use super glue to hold the connecting end together.
After this, just clean the box of any extra cuttings. You can also decorate it in various colours if you like.
Fill the box again with the manuals, other accessories. There you go. Now you have your very own dock for your Samsung Galaxy S III.