Here are a couple of useful websites and resources that may help you on your 3DS hacking quest.
3DS Homebrew, CFW, and Downgrade Help
- Nintendo 3DS hax helper – Really intuitive website to get you started on getting homebrew onto your 3DS. Even includes guides on how to downgrade firmware to get custom firmware. Highly recommended.
- Smea’s 3DS Homebrew Launcher Site – Provides a good overview of what homebrew is and the different exploits available. Find the “homebrew starter kit” here.
- 3DBrew Wiki – Reliable wiki dedicated to homebrew on the 3DS.
- GBATemp Wiki – Pretty good wiki that includes information for homebrew and flashcarts on 3DS.
- Plailect’s OTP and full arm9loaderhax CFW Guide – everything you need to know on how to install Custom Firmware on your N3DS/O3DS/2DS. Click on get started after reading the home page.
- TitleDB – an up-to-date list of homebrew applications
3DS Themes and Customization
- 3DS Themes – Get custom themes for your 3DS Home Menu. Also find custom badges and splash screens for CFW.
- 3DS Theme Swap – Request and submit custom themes in this subreddit. Includes links to many themes.
- GBATemp Custom Theme Thread – Discussion thread where you can post your own custom themes and compilations.
- Background music for custom themes – Resource for finding BGM for your own custom themes.
- GBATemp – Huge community focused on Homebrew for all major systems including 3DS.
- /r/3DSHacks – Subreddit
If you would like me to include your site in this list, contact me.