It seems that I have really messed up with the packaging of the single Explorer boards- I apologise for that profusely. The brown tape that was used for the first despatch run has not stuck at all well and is not holding the box together. On top of that, there wasn't any bubble wrap used to cushion the PCB. The boards that went out yesterday have all been taped up better with different tape which will hopefully prevent the box from coming undone. The Inventor's Kits use a different box and are well packaged with bubble wrap.
Please check your boards carefully and if you are not happy for any reason please let me know and we'll work something out.