臻於完善

于 = 亅 + 二 : Mnemonic symbol: prepositions (in, at, on, to, ...) are what glue the sentence together. Honey is as sticky as glue, so I'll represent 于 by a honey jar.

Yu the Great (于) was assigned to repair the electronics of the space station's kitchen (Ø2), but instead he was snacking honey from a honey jar (于). Unfortunately his capacitor (二) got stuck in the honey and now he has to use a crowbar (亅) to lever it out.

完 = 元 + 宀 : In other characters: A checkered flag.

完 = 元 + 宀 : Willy Walrus celebrates finishing his degree just inside the anthill's kitchen. He wears a graduation cap, gets lots of coins and somebody waves with a checkered flag.

善 = 业 + 口 + 羊 : Mnemonic symbol: a good book about etiquette.

Sherlock Holmes (sh) finds a bullfrog (业) and a sheep (羊) fighting viciously over a mandarin (口) in the anthill's bathroom (an4). He finds this behaviour unbearable and starts to read Emily Post to them to teach them some manners (善).