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I have tried all the stuff on the market... some works better than others. Many toys have really hard to remove finishes and they are best removed by sanding. Also you don't know exactly what type of plastic they are; usually ABS or something kinda rubbery.
Brake Fluid - slow but it does work. I have had instances where it would not touch some kinds of paints or it would, say, remove "yellow" but not "white". Also some brake fluids can melt plastics. I don't use it now since I don't feel like taking 2 months to strip something that other products can do in 10 minutes. It can discolor or haze clear plastic.
Poly Scale ELO Easy Lift Off- it does work, especially on acrylics. You can't just soak parts and walk away. It can and does/will melt plastic. It is also NOT safe on resin as it turns resin into goo. For the price its expensive if you have to soak something large. For small stuff it works ok if you watch it like a hawk.
Oven Cleaner - not bad and it works on enamel and acrylic paints. THe fumes are tough, so work outside. Mr. Muscle was my favorite brand but its hard to find. It would strip paint off down to bare plastic in about 5 minutes, with minimial scrubbing. Try to get the cheap caustic stuff versus the new "less toxic" varieties. Easy Off works ok. I use a plastic shoe box and just spray a thick layer over the item and let it sit. Usually I will rinse and repeat, with a light scrubbing with a tooth brush on the second application. Some plastic gloves are helpful.
Super Clean/Purple Power these are my favorite paint removers. They remove all kinds of paints fairly quickly. Depending on the paint, when it was applied, etc. it will start to lift off in 5 minutes. Usually I soak stuff overnight and that does the trick. There isnt much scrubbing the paint is just gone. You can buy these products at Wal Mart in the automotive section, Auto parts stores, etc. Wesley's Tire Bleach works good too. Same basic idea. It's resin safe too and you can use it to both strip badly painted resin but also to prep resin castings. Purple Power will remove any oils, mold release glop, etc. It is also safe on clear plastic. You can buy these in gallon size bottles that are economical and good for soaking larger models and items.
Testors thinner/Mineral Spirits - a quick wipe will remove some enamel from a plastic part, but any kind of soaking will damage the plastic.
Acetone/Nail Polish Remover - again very hard on plastic and not recommended. Acetone is an industrial grade solvent.
Windex - removes acrylic paint nicely and its pretty inert and inexpensive.
Rubbing Alcohol/Isopropyl alcohol - removes acrylic paint and is a good thinner for most hobby acrylics.
Tamiya Lacquer Thinner/Gunze Mr. Color Thinner - these two products, while expensive, are exellent for paint removal. While they are lacquer thinners they are PLASTIC SAFE. I stripped some parts on my Moebius Moon Bus with the stuff. The nice thing with both of these is they will remove Acrylic, Enamel and Tamiya lacquer spray paint INSTANTLY. Tamiya sprays are pretty much permanant otherwise. It would cost a fortune to soak something big, but for smaller stuff its the best thing yet.