国库

国 = 囗 + 玉 : Mnemonic symbol: a nation's flag. Let's say the Chinese flag.

In the observatory's kitchen (o2) Gitta Giraffe (gu) is practising her ballet performance. She got a whole crate (囗) full of jade bracelets (玉) and flags (国) and fixed one flag to each jade bracelet. This makes a perfect combination for throwing the ring with the flag waving behind it and catching the ring again after a few pirouettes.

库 = 广 + 车 : Karl Koala (ku) ordered a new cabriolet (车), and it's going to be delivered to his garage (库) in the space station's bathroom (Ø4). The new cabriolet is being thrown off suspended from a parachute (广), but unfortunately it hits the garage with Karl's old car and smashes it.