This replaces the bottom portion of MarkBensons "Prusa i3 Spool Mount" with a stronger design. Side have been added to give "I-beam" structural effect and more material has been added.
My original spool mount broke after two days from the weight of the spool. If printed well, this one will last you a long time. Print two of them.
Use the remaining parts from MarkBensons Spool Mount to complete.
Print in upright position in order to get best bridging.
I used a 4mm brim in Slic3r.