Project ideas for a bored teenager

Question is title: I'm on vacation and I'm very bored.

Please give me some ideas that make me actually study something and gives some nice results. I am reasonably confident in writing rust code.

Thanks in advance!

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Edit: wow, thank you so much. I can't respond to each suggestion individually. But thank you very much. I'll consider all the options with care and decide on something. But really, thank you!