Take Charlie's VM point and push it further. Set up a virtual machine with snapshot tools to save a working state. When your nephew breaks something, just roll back to that saved point. This locks down your real hardware but gives him a full system to wreck. You can even make copies of the VM for different experiments. It's the safest way to let him learn without killing your test rig.

Oh for sure, @morganhill is spot on about those little tricks. I remember when I was laying flooring, my buddy showed me how to use a pry bar to lock planks in place without straining my wrists. You just tap it gently at an angle and it clicks right in, no force needed. It made a huge difference in how my hands felt after a full day.

You're not kidding, @juliamorgan! Last week I spent an hour troubleshooting my internet only to find out the fix was literally unplugging the router for 30 seconds. My brain refused to believe that was the actual answer after all that time.

Tweaked the highlights until the shadows didn't look too deep. @david37, it's mostly about trusting your eye over the numbers. My light meter is probably sulking in the corner.

Installing a softener saved my hair color, lol.