無故

无 = 一 + 𠂇 + 乚 : Mnemonic symbol: the philosopher Diogenes, who has nothing and wants nothing.

无 = 一 + 𠂇 + 乚 : Just inside the space station's entrance, Diogenes is annoyed by Willy Walrus, who's playing his flute. Diogenes just wants a peaceful time without being disturbed, so he cuts the flute into pieces with a pair of scissors, and threatens to beat Willy Walrus with a shovel should he annoy Diogenes again.

Mnemonic symbol: 無爲, wu2 wei2, the state of non-doing after having attained complete harmony with the Tao.

Willy Walrus (w) has attained Wu Wei (無) just inside the space station's entrance (Ø2), while from the outside it may seem like he is napping.

故 = 古 + 攵 : Mnemonic symbol: This character only appears in 做, so we don't need a strong mnemonic symbol. We should be able to refer to 故 when we think of 故事 or 故意. Because it fits nicely to its components, I'll think of it as in the meaning of 故墓, an old grave.

故 = 古 + 攵 : There is an ancient cloister in the space station's bathroom, and Gitta Giraffe once heard a story from her fellow astronauts that there's an old tomb inside with lots of treasure. One day she can't hold herself back anymore and deliberately breaks the cloister open using a sledgehammer.