Tooth sticks and wood glue. Cheap and works perfectly.

Not sure about clay bricks, but it’s an amazing cork

My cat

To me, training our ears is part of the learning process. I’m no talking about recognising which note is being played, that’s another story, but to perceive when something is off. It’s very important when learning to bend the strings. If your guitar is not in tune, your ears don’t learn. I tune it every time I start playing, usually once per day, unless notice that something is off. And more frequently when recording.