The root of a stamp is to get an instant picture down. Back in the olden days, people had to make seals and draw out things by hand, so stamps came about so you can—BAM—just stamp it and have what you want in an instant.
Think about the thing you want to make instant. I'd want instant socks (そく)! Don't waste time searching for a matching pair or pulling them on. Just take out a pair of instant socks, add water, and the socks are already on your feet. In an instant!
Currently there are no similar looking kanji which exist in the WaniKani learning system