Starting putting together a Gundam model, got to the third step, put something together wrong, can't get it to come back apart to fix it.
ETA: HA! I was sitting on the toilet with half a Gundam leg, as one does, and spotted the tiny scissors I use to cut my bangs, so I stuck them in the opening and tried to open them up, cracking the connection between the two pieces open enough to get the rest with my hands. Now the leg can bend properly!! (If I had installed it this way one would have bent backwards. Fun!)