oh well when doing custom paints on transformer if u can take it apart ofcores do so but some times its a real pain like in my last one an animated prime repaint i wanted the chest silver but not the front windows cant really take those out so masking tape
well if i want a full color cover i use the blue masking tape to cover what i dont want painted. like the stuff i used on iron man i get that in the paint dep at walmart. far as the paint goes what ever works with plastics cause some paints will melt plastic. krylon tends to work best for me. then for detail work i use elmers painter pens i get those in the arts an craft section walmart and then i use a gliter clear sealer (theres no gliter in the sealer) and its really just time and Patience ill put down a base coat color wait about 20 hours then detail wait 2-5 hours then clear seal wait min 14 preferable 24 hour then u should be good