I have a daughter (not Cindy Lou Who, but she is slightly less than 2) who loves buttons and lights ("yight!").
If something looks like a button, or looks like it could be a button, she'll press it. Repeatedly - especially if it clicks! Clicking buttons are the best, and I'm glad things like dishwashers come with button locks now.
She's also learning colors and letters. I had some time off over the winter, so I built her a button box that's useful for all of these things!
This is the non-absurdly-technical description of my build. If you're looking for the gory technical details with an awful lot of advice about how not to do things, you'll want to check back next week for a radically longer post.
Otherwise, read on for how I built her button box!