I do a lot of modeling, mainly on miniatures for wargames (Warhammer, Warhammer40K, etc) and have looked for easys ways to remove paint from the plastic and metal minis. Wanted to do it without using anything to damage the plastic. I've heard of using everything from break fluid to engine cleanerand so forth. Only problem with these cleaners, as well as others is smell and having to use safety cleaning gloves. I have stumbled across the best solution: Pine Sol. You don't need to use gloves to work with it, you can do it in a well ventelated area but it doesn't have to be outside or use a breathing device, just open the windows, use a fan to blow the smell out and get a toothbrush. The Pine Sol won't hurt the surface of the plastic or metal at all and all you have to do is soak it for a but.

Put the item in a sealable container (glad plastic storage containers work great) and fill the container til the entire item is covered in Pine Sol and put the top on the container. Let it sit for about a half an hour up to as long as over night. You can just rub the paint off, peel it off and use a tooth brush for the recessed and detailed areas. It will start to come off after a half hour and it can soak for a long time with no surface damage (I had a piece sitting for 2 years I forgot about).

I have done this to plastic and metal models but not to resin. I will assume it will work on resin but will take no responsability if it does not or if it damages the resin piece. Also I have only tried this with Acrylic paint so far and have NOT tried it with enamel yet. I don't use enamel paints so I don't know.