Meta, buddy. lose the valve cleaner. It'll destroy the plastic, or at least haze it really bad if you arent careful. Trust me, I've been there. Best technique is to get a large plastic tub, like under the bed style, and then go to the drugstore. Most drugstores will sell large bottles of isopropyl alcohol. look for something that 70% alcohol or better. fill the tub with it. My tub takes about 6-8 bottles, depending on piece of plastic. put your part in, and soak it. any of those standard nylon dish brushes will do the job to get the gray paint off. personally, I use a Black & Decker Scum Buster, but thats me. Regardless, let the plastics soak for 30 minute intervals between scrubbing. before you know it, all the paint will be off, and you'll have a perfect shell. Then you can strain the alcohol through cheese cloth, back into the bottles. (I run mine through a cheese cloth, then a coffee filter) you can reuse the alcohol over and over again.

Sorry, didnt mean to teach class there. I'd just feel bad if you hazed a whole project with valve cleaner, and I'd said nothing.
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Electricity tastes good. No, seriously.