For a project I need to program a few microcontrollers in the same circuit. This meant I needed to plug the programmer around on the board a lot. This got annoying very fast. Therefore I decided to make a switch box. In my junk pile I found an old switch of a, parallel port switch. This has 4 positions and a lot of contacts. For the ICSP I only need 3. However in some circuits the supply voltage is not common. Hence, I chose to also switch the power supply connections. For the connections to the circuit boards I used DIN connectors, for the simple reason I have lots of these.
Inside the box: