One of my best sounding projects; a 3 watt amp board mounted inside of an old, metal classroom wall speaker (the kind used for announcements). The speaker probably dates to the 60's or early 70's. I find that old speakers that are small hold up up better (speaker cone deterioration wise) than a lot of the bigger ones so it's pretty safe to buy them on eBay. These types of boxes are currently increasing in price for some reason. Maybe that's due to the great sound you can get out of these with a $30 amp board and an hour's worth of work!