My father made this for me when I was a kid.  Not sure where he got the idea.  My parents brought it when they drove up this summer, thinking that M would be interested in a few months, but it’s now one of her favorite toys.  She can entertain herself while I make dinner, opening the door, taking a toy out, closing the door, opening the door, putting the toy in . . . and so on . . . over and over.  She has the eye hook down and can hook and unhook it, which is unfortunate, since that’s how we keep her confined to the house and out of the backyard, where she loves to swing! (We also have one up high, don’t you worry!)