Last week, I have received a cute card with 'I love you mom' written in Japanese (starting at the bottom and going right to left, so cute).
The other morning we were painting and I randomly did a tree and painted ki on the paper as well. B declared it a giant card and asked for more. I did a group of trees and was about to write mori when B asked for the brush - he tried to write ippai ki. You can see it above the trees, in green paint. His i sometimes looks like ko and he missed the tsu, pa, and second i but that's okay.
I don't know if I'll make more - this does seem like a nice way to introduce vocabulary, but it kind of turns something fun into work. Then again, B just thinks it's fun.