故此

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.

此 = 匕 + 止 : These boots are made for walking! The King of Chu cannot get his boots off in the space station. First he tries with the help of a large ladle, then he switches to a big barrier, which finally works.