50mm Extruder Fan Duct / Adapter - Printrbot Simple

My extruder fan died on my printrbot, but I did not have a spare 40mm fan laying around. Rather than order a new fan I just grabbed a 50mm that I had and designed an adapter / duct for it. This will adapt a 50mm cooling fan to the existing mounting location for the stock 40mm fan on a printrbot simple makers edition. This does not interfere with the GT2 belt conversion by iamjonlawrence.