Ah! The colour laser is key. If you have a black laser it will do the equivalent job.
After doing the design in something like photoshop, print it directly onto clear adhesive pvc - in the same way you do with press n peel (print it on paper first for positioning then cut out pvc sticker to suit and hold in place with masking tape) - I found sign printing shops will sell offcuts dirt-cheap
After that, cut out another unprinted piece and carefully place it on top of the image to seal it in.
I found a ruler is the best way to smooth it out with as few bubbles as possible. Once it's stuck on, use an exacto knife to get it to the size of the front face of your case.. Also, give the front a wipe to remove any gunk or fibres. The smallest hair is going to PISS YOU OFF, trust me.
Positioning it perfectly is the hardest thing, I found.. and not getting all the adhesive side smudged up by fingerprints in the positioning process. Maybe rubber gloves would help this

..If you get it lined up perfectly in the first cm, the ruler comes in handy again.
Remember to note the background colour it's being stuck onto. Seeing as the colour you'll see on your screen is referenced with a white background. The CMYK is only a thin layer when printed and the white paper does a lot of the work to make it appear similarly.
If you had a yellow case, and the sticker contained blue, it would most likely appear with a greenish tint. Keep this and mind and just play around until you get it right.. At the end of the day, a white case would probably yield the best results. Powder-coating is cheap though!
