Toothpaste is great for your teeth and for your wall. One of the simplest solutions to repairing a nail hole in drywall involves using toothpaste. You take toothpaste and push as much as you can to fill up the hole, scrape off any remaining paste to make a nice smooth surface and then let the paste dry. Toothpaste really looks surprisingly similar to spackling and does not shrink like caulking does.
Use a clothespin to hold a nail whilst hammering and thus save your fingers.
Use half of a pool noodle to protect your car door from slamming against the garage wall.
You can easily implement this idea, used in poor countries like Filipines, to have some natural light in a room… with just a water bottle!