I'm interested in making connections to gpio and breadboards strong enough to jostle around a bit, but make them temporary enough to change on a whim. A recent MagPi article mentions Blu-tack and Plasticine. I have Fun Tak on hand, but don't want to use it if it will "muck up" my Pi. Does anyone have any experience using this product on their electronic projects?
Soldered joints ensure both good mechanical and electrical connections - fun Tak is unlikely to provide a suitable mechanical bond in such small spaces, nor is it likely to have proper electrical conductivity.
However, something like the Pi Cobbler and ribbon cable from Adafruit will allow you to separate the Pi and the breadboard when desired and not require any soldering (assuming you buy a preassembled version).
You don't mention what model Pi you are using but some soldering may be required if using the the new Pi Zero - which does not have the GPIO pins populated) If using the Pi Zero this affords some additional options. In addition to the standard male pins you could use a female header, this would allow using standard male to male jumper wires to connect to your breadboard, Additionally you could use a set of right angle headers to create a vertical mounting for the Pi above the breadboard (akin to a video card mount in a PC).