Step 1: Step 1
Simply cut out a fairly big rectangle of card.
Step 2: Step 2
Now, fold your piece of rectangle in half and cover it with duct tape.
Step 3: Step 3
Next, cut out a very small rectangle of cardboard and cover this with duct tape as well.
Step 4: Step 4
Cut out a big square of cardboard, cover it in duct tape and stick it to your first piece that you cut out. Finally, stick your small piece to your first one and it should look like the picture above. Now, you just need to hang your keys on it! (I've circled where.) You can use masking tape or Sellotape to create other effects!