Quadcopter F450 Arm Shortened

UPDATE 2/23/2017 The arms are redesigned for a carbon fiber rod (5mm OD) reinforcement. Buy some 5mm OD rod and cut it to 118 mm lengths.

This is a remix BUT I can't find the original STL file. I want to rebuild my Cheerson CX-20 quadcopter in a F450 style frame but I wanted the arms to be shorter. Using Tinkercad I removed the center of the arm and joined it back together. I also removed what I fell is excess plastic down the center. The original file had a hump running almost end to end. I