Rectangular Piston

I made a cylindrical piston before which came out great except for a few leaks. So one day i got the idea of trying out another shape starting with a rectangular piston. I designed the walls to be a lot thicker in case the corners ever became critical points if the piston were to start storing pressure. The print was coming out great until I heard a loud pop from my makerbot. Upon further inspection, I found my idler wheel had snapped. Fortunately, I have a spare idler wheel and hopefully will only be out of commission for a day.