So I was doing my lessons and I saw 材. Sometimes I look up things to see if I can find anything interesting to remember it by. I found this video: https://www.youtube.com/watch?v=ryA4CmkhFRc It’s a giant wooden xylophone! Perfect for remembering lumber and ざい. A genius used a tree to create lumber to create the xylophone!
Anyway, it helped me stick the mnemonic in my head so I thought I’d share 