Yep, quart/liter pop bottle works great. Easy to cut and you can squeeze it in there. Almost no drips and cheap! I remove the voltage regulator too. Use a long socket on my Makita and the nuts are off in a jiffy. Also makes it real easy to clean up the frame in that area too. I also clean up the heat sink fins on the voltage regulator while I have it loose. The cooler you keep your electronics the longer they will last.