Sounds like an engineer in the making
Does your son have science sets, Legos and erector sets that he can play with? My guess is that he is just taking things apart to see how they work. Most engineers that I know can probably relate to destroying a few toys (and other things!) at one time or another. Trust me...the toys are just the beginning. As we get older, the things that we take apart for the heck of it are just bigger and more expensive 
Does your son have science sets, Legos and erector sets that he can play with? My guess is that he is just taking things apart to see how they work. Most engineers that I know can probably relate to destroying a few toys (and other things!) at one time or another. Trust me...the toys are just the beginning. As we get older, the things that we take apart for the heck of it are just bigger and more expensive 