Magnetic shelf holder

Magnetic holder attached to a shelf. I created this thing to set my speaker under a shelf without using screws or any kind of adhesive, so no harm it's done to the shelf or the speaker. Also, the speaker can be oriented easily. But I think it can be used for more purposes.

I used a 5 cent Euro coin because it can be attracted to a magnet. You can find a magnet easily inside a hard disk drive. Two magnets are enough to hold the speaker and can be hidden with the piece "cover". You also need t