You may have seen these advertised on TV and wondered if they work-they do!  I happened upon Attach-its a few years ago when browsing through the big box hardware store.  The package had been marked down so I took a chance and bought it.  A few weeks later I had the opportunity to put them to the test.  I needed to hang fairly heavy pictures on a wall but an air return duct was located directly behind the wall.  Years before, the clients hit metal when they tried to hang the pictures on the same wall so the expanse remained bare for years. 

Attach-its are mounted on the object and then you simply position the piece and push it into the wall.  The hardware makes small, thin slits into the wall rather than holes.  The prongs rest on the drywall.  Because they only need to be as deep as the drywall, you can use them in cases where you might otherwise drive a hole into metal ductwork.

I have used them in my home to hang heavy mirrors that otherwise would have required using the keyholes in the back.  I don't know about you but I can't stand working with those things since they are often uneven or off in some other way.  The Attach-its have worked beautifully.

The only time I have had trouble is if the wall is slightly bowed.  You can build up the surface on the back of your object with the necessary thickness of wood to compensate for the bow, securing it to the object then adding the Attach-it.

You can buy these in bulk from the manufacturer or through Amazon. They come with a mini leveler called Level-it.

Attach-its