How to store Bitcoins for 100 Years?

Yes, you read this right. The national library in my country is organizing an event where you can write letters that will be opened in the year 2122. Now I thought it would be interesting to put some coins in form of the seed words or private key in an enveloppe. I thought maybe 100$ in btc would be an idea. What do you think? Now back in the days I just would have put everything on a paper wallet. But today? Just the seed phrase to a wallet? But which one to choose? Hope to get here some ideas