I wanted a simple one piece spool holder for my Prusa I2. None of the other designs I found quite met my needs. A couple would not even fit on my bed. I wanted something similar to what I had on my I3.

I think I may make a new version a bit wider so it is a little stronger at the bend.

This design is set up to be clip across the top two horizontal bars. Put the center slot on first then tilt up until the end slot clips into place.

Print with a pretty dense infill and several shells for strength.

The positioned version is layed out to fit on my I2 build plate. You may need to play with the positioning your self depending on how your print bed is aligned with the endstops and physical limits of the printer.