Buying a bitcoin and burying it.

So I've been lurking a bit and while am not really interested in the daily trading of it i would like to buy a coin and stash it away for some years just in case it does explode in price in 5 years or whenever, maybe give to kids, etc... and saw that you can put the ability to use the bitcoin on a physical object and it becomes basically unusable without that key or password.

I tried google buy found places trying to sell cold wallets, what im thinking more of is that i can use my CNC mahine to CNC into some aluminium and bury that sucker in an undisclosed location ;)

So should i take the leap and buy a coin how can i store it as outlined? Could someone point me to a guide or is it somehow just a key that you have to write down like a save back in old video game days?

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Thanks!