This project took me about three hours, slightly because I'm a perfectionist, but mostly because I'm not that good at picking out things that just won't work with the project. Total cost was around $20 (mind, I had some supplies already), and everything can be found online at a doll house building site, or at the hardware store.
For this you will need:
Six panel dollhouse door (like so)
Cheap wooden stir stick or popsicle stick
Fimo clay or another modeling clay to make the door knocker
A gold number/letter sticker (one of these - go for the letter L because you get more gold space)
Gold paint pen
Glue - I used white glue
Wire to hang the ornament with
+Gloss finish if your black paint isn't shiny.
Keyhole plate with tiny nails (these, though can be switched out for something different)
Step 1: Painting the parts
Note in the picture the painted coffee stir stick, and the small black 'lip'. This lip comes with the dollhouse door, as it (and two other pieces) make interior trim if you're building a dollhouse. I am not, but used the piece to give my door a top ledge.
The stir stick was cut to size and glued to the bottom of the door, as a door kick.