The method I use is to get a medium sized screwdriver with a lumpy handle, like this
![](http://choicediy.co.uk/images/SD101_ENWWMPRO1.JPG)
Hold it near the end of the blade, hold the victim
loosely in the other hand and repeatedly hit it at the join, working all the way around, gradually increasing the force until you hear the sound change, indicating the seam has cracked. Once you get the first crack you can then usually progressively open it up using with the same method.
Most times this will seperate the two halves cleanly at the join, and they can be glued back again afterwards if required. .
This method also works well on most battery packs.