On GAGA-1 the flight computer was screwed in place using nylon bolts that went through the polystyrene walls of the capsule. GAGA-2 is using cable ties.
One concern with cable ties is their performance at low temperature. The CUSF guys had warned me never to use cable ties for load bearing joints. But since we are holding in place a few grams of flight computer the only remaining concern was whether the cable ties would still be locked at low temperature.
So, I locked together a pair of ties and left them in the freezer at -18C overnight.
Here's the flight computer inside the capsule:
Then there are a pair of cable ties that pass through the wall of the inner capsule. Those cable ties are hot glued in place so there are no holes and so they don't move.