If you don't want to shell out for a portable speaker stand for your phone or other MP3 player, Etsy user Lowell takes advantage of physics to make a cheap, wooden block act as an iPhone speaker.
We already know you can amplify the sound from tiny speakers with household items — whether it's a bowl, some paper cups or a drinking glass — but if you want a better solution that doesn't cost as much as a portable speaker (or run on electricity), you can hollow out a few sides of a wooden block, create a slot for your device, and play music through your device's speakers. It should be well amplified through the wood.
You can already buy this "speaker" from Etsy for $US60, but if you're going to spend that much, you might as well buy a real speaker. Any seasoned woodworkers could probably make one of these in their garage for much, much cheaper, and make it compatible with more than just the iPhone 4, so check out the Etsy page below for more info on how it was made.