This is a simple upgrade to IKEA Tertial lamp. Just print all the parts and assemble them in the following way:

• Move the front element into a trapezoidal hole, temporarily fix it in place with a stripe of a tape.
• Lay the lamp flat so that the front element is firmly laying on the table surface.
• Press the back element into the front element via a hole on the other side of the lamp. Help yourself with a small hammer.
• Remove the tape. Both parts should be fixed in place now.
• Push the hook through a square hole in the front element so that it entirely fills it and not sticks at the back.

Hooray! Now you have a pretty versatile hook on your lamp. Hang your headphones, hairbands, keys or whatever you want!