Summary

This hanger fits many types of bookshelves.
My purpose of this thing is to hang a calender on the side of the bookshelf.

Instructions

I sliced this with MakerWare.

Settings for Hanger.stl:
MakerWare Medium
Infill: 20%
Shells: 2
Layer Height: 0.2
Temperature: 230c
Extrude speed: 40 mm/s
Travel speed: 150 mm/s

Settings for Hook.stl
MakerWare Fine
Infill: 20%
Shells: 3
Layer Height: 0.1
Temperature: 230c
Extrude speed: 20 mm/s
Travel speed: 150 mm/s

I had to trim the hook to fit in the hanger, but no glue seams to be needed.