Ask HN: How to come up with a useful, coding hobby project?

I get bored on weekends. Of course I go out and do things, but I also find myself bored at home sometimes with not much to do, lots of mental energy, and not in the mood to watch TV shows or play video games.

I'd love to start a hobby project that:

* ..would teach me something new (i.e. TCP protocol, or redis, or..) * ..would keep me "entertained" for potentially 100+ hours * ..I would NOT be tempted to start monetizing. It has to be absolutely useless

As an example, some time ago I had fun implementing this book: https://www.amazon.com/Ray-Tracer-Challenge-Test-Driven-Renderer/dp/1680502719

This time I'd like to go deeper into some other topic; I don't think I spent more than 20 hours cumulatively on that book.

How about contributing to the opensource

I'm confused... do you want useful or useless

May things started out as a 'just need to get this done.'

Per hobby, look at various things do on frequent basis and/or infrequent basis. Try to envision how to do all/or parts as a coding hobby project. Then go do the opensource research to see if there are things that do something similar (or just specific related aspect of what want to code/do) . Jury rig / program way to get the open source things to work together.

Eample: frequent tasks/appointment & schedule reminders (enter task & do automated sms notification reminders) which would entail setting up OS, datbase (command line and/or gui), 'shell scripting' link between user / database and SMS. Perhaps upcoming scheduled report summary & automated clean-up of expired tasks/schedules.

perhaps at some point move it over to cloud so can visually access / add additional information through internet portal. might want to make sure understand security implications first.

> I would NOT be tempted to start monetizing. It has to be absolutely useless

You stated that you want a useful one in the title