It may sound like an old method, but I find it unique and effective.
" Inside the box is a small wooden box (which needs to be opened with a small key)
with a thin glass bottle and thin paper wrapped around the bottle,
which is written on it "Bitcoin BTC Seed. "
That means:
If you try to open or break the wooden box without the key, the glass bottle inside will break and acid will come out and destroy the paper writing, so there will be no chance of theft!!! I thought that instead of acid, using lemon juice and light pen writing would be much safer.
(If you don't have a hardware wallet, you can think about it.)
Have you thought about losing the key to the lock? This method is fine but it is not free from risk which is losing the key or another person gaining access to the key without your approval. Hardware wallets still remain the best and safest way but it comes with a lot of burden as well and in the absence of that then steel capsule is my choice to store my seed phrase. I think getting a marker will be cheaper and affordable for anyone who does not have a hardware wallet.