The downsides

If the idea of grinding, soldering, cutting, and more grinding doesn't put you off building one, here are two things which probably will.

1. You get a NES controller. Chances are it's used by someone who actually used it since the 80's and so when you open it up, you'll be greeted with a nice surprise.

Be prepared to get cleaning when you get open your NES controller.

2. Chances are when you decide to get building, desoldering is something that you can't avoid and the next picture shows what happens when you rush a desoldering job.

2 of the 6 solder pads have lifted right off. That is another MP3 victim all because I decided to rush it. At the time of writing, I'm not sure how this could be fixed but I'm sure it could've been fixed but I don't know how. So there you go. Just SOME of the ways in how building a NES MP3 Player can go wrong.