The 3DS homebrew community has made some unbelievably cool stuff!! Here's a doc that walks you through a bunch of the stuff you can do with links out to just about everything you need to hack your own safely:

https://docs.google.com/document/d/1Y-6FGCreVMd7KVyes1rvIroEyJjC9KXQ9vQz72Tq15w