Learn how things work. Take them apart. Try to put them back together again properly. Buy sacrificial items at thrift stores/Goodwill/Craigslist for this. Look for broken/worn out items and try to make them work better. Small kitchen appliances are a great place to start. Sometimes all it needs is to be taken apart, cleaned and relubricated. Collect common components (motors, screws, magnets, springs, wiring, lights) from the things you can’t fix, and recycyle the rest if possible.

As you take things apart, pay attention to how the different pieces are connected. Take pictures for later reference. Look at it and ask, why this component and why is it oriented this specific way inside the appliance and connected to that other component? What function do the two parts accomplish together? What were the design choices that led to this arrangement? And if applicable, which part of it broke, and what was the likely cause, can it be fixed, and can the failure be prevented in the future?

You can really learn a lot by taking things apart, even if you’re not able to fix it.