MB3 106b: When are Utensil Covers Muktzah? (308:9-11)

The door/cover of a storage container can be reattached (אין בנין בכלים) but not in a permanent fashion (מכה בפטיש). A cover over a pit is muktzah unless it has a handle.

Using a sewing needle (כלי שמלאכתו לאיסור) on Shabbos to remove a splinter.