Improved Heatsink/Fan Spacers for MakerBot Replicator 2

I recently had to do some maintenance on my Replicator 2 that required that I disassemble and reassemble the extruder assembly many times. I got really tired of the spacers rolling off the edge of its platform, and of poking around somewhat blindly with the screw through the fan, often missing the spacer entirely.

These spacers are square, so they don't roll off. They also have a larger opening on one end so it's easier to guide the screw in.