Students are killers! After the painful death op three raspis I decided to design a short circuit resistant buffer board. A little googling pointed to this page from brian dorey. The mentioned TXS0108E sounded interesting and the design was straightforward. Because of the raspis multiple GND Pins it was possible to come down to only 20 pins and so freeing some space on the breadboard. More infos on weigu.lu/c/rpibuffboard