Custom Themes

3DS custom theme FAQ

There seems to be a lot unclear about this subject, so I thought it could be useful to make a FAQ about it.
If you have any questions ask them here, if you have an answer for a question you've seen a lot also post it (with the question) and I will add it to the list!

Q: How do I install a theme?
A: Download https://github.com/yellows8/3ds_homemenu_extdatatool/releases
Copy the body_LZ.bin (and bg.btstm) from the theme into /3ds/3ds_homemenu_extdatatool or to the root if you're using gateway.
Use the tool to enable cache (If you had a DLC theme selected it's already on but it doesn't hurt to check!) and then copy SD theme cache to extdata.
You can now go to the menu and the theme should appear

Q: Do I need a DLC theme for this?
A: No, but having one does have benefits! If you have a DLC theme selected and then install a custom theme it will stay after a reboot without it you'll have to enable the cache and re-install the theme every time. If you're using a gateway it should't matter as soon as gateway allows for unsigned cia's!

Q: What files should be included with a theme?
A: Most themes will come as body_LZ.bin and if it has background music with a bg.bcstm file (but they can have a ThemeManager.bin file though not common nor needed)
Cache dumps (most likely for pirated themes) will have 3 files:
- BodyCache.bin
- ThemeManager.bin
- bg.bcstm
Cache dumps of mulitible themes at once (9.3+) will have these files:
- BodyCache_rd.bin
- ThemeManger.bin
- bg.bcstm
Gateway themes will be in .cia format (but won't work unless signed!)

Q: Does this overwrite my theme?
A: No, you can choose another theme and then the original one and it will turn back to normal. This is because the tool (by Yellows8) only overwrites the cache witch is replaced when another theme is chosen!

Q: Can you pirate themes with this tool?
A: Yes. (Anyone's cache dump of a DLC theme will work (They are not version specific but BodyCache_RD.bin only works on 9.3+ all others work with any 9.x+ firmware))

Q: Are themes region locked?
A: No.

Q: How long will it keep my own custom theme?
A: If you have a DLC theme (and have it selected) before injecting cache it will stay until you either replace it or load another theme, if you don't it will stay until you close your 3DS, open a game/app or reboot your 3DS (basically useless).

Q: Can I make my own themes?
A: Yes, if you want to know how here is a simple guide by ChrisCerne:
If anyone of you is having trouble making your own theme, here's how.
  1. Download the tool here (https://gbatemp.net/threads/release-theme-customization-tools.374206/)
  2. Create a new BLANK BMP image with the dimensions 512 x 256 pixels for the top screen.
  3. At the coordinates (0, 0) of that new image, insert the picture you want with the dimensions of 400 x 240. This will be the top screen.
  4. Create a new BLANK BMP image with the dimensions 1024 x 256 pixels for the bottom screen.
  5. Starting at coordinates (0, 0) of that new image, insert the three different images you want to transition on the bottom screen.
  6. These three images should be each 320 x 240 pixels, and at coordinates (0, 0), (320, 0), and (640, 0) respectively.
  7. Remember that these images will not fill up all of the white-space within the container BMP images. This is supposed to happen.
  8. In the 3DS Theme Editor that you downloaded in step one, import the default theme by pressing File>Open and navigating to data/body_BZ.bin.
  9. For slide 0, press File>Import and select the BMP Image you need for the top screen.
  10. For slide 1, press File>Import and select the BMP Image you need for the bottom screen.
  11. Once you're done importing, press simulator to do a test-run of your theme thus far.
  12. If you're happy with your results, press File>Save to save your body_BZ.bin file.

Q: How do I add sound to my theme?
A: First make a .wav file with a piece of music (The file must have a size of 0x337000 or 3.371.008 bytes you can fill up extra space with 0 bytes using a HEX editor)
Use Every File Explorer (https://gbatemp.net/threads/release-every-file-explorer.373615/) to convert it to .bcstm (File -> New from File -> Nintendo 3DS Plugin -> CTR Stream -> open .wav -> save icon -> save as bgm.bcstm)

Q: Why do some themes have a white box at the top left?
A: This is most likely a small bug in the theme maker! You'll probably have to live with it for now.

Q: Why do many themes have folders with a mario bullet on them?
A: This is the default folder for the custom theme tool, this means that many theme makers didn't change it.

Q: Can themes have custom icons for games?
A: Most likely yes, but none have at the moment (and it's unsure when the tool will support this (and if we can even do this!))
For documentation on the cached icons that could be edited: http://3dbrew.org/wiki/Home_Menu#Cache.dat_.26_CacheD.dat

Q: Does this mean NINJHAX has kernel?
A: No, however it is able to read and write both NAND and SD extdata which is still cool (and might be useful)
 

tyons

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the max file size of the bcstm must be 3.371.008 bytes, for what I understood (I tried with one of 3.371.024 bytes by mistake and 3ds_homemenu_extdatatool said that it was too big).
 

tyons

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ninjhax, gateway or custom firmware?

edit: *sees post below* I didn't say that I knew the answer, I was just asking what you use in case it was possible >_>
 

GotKrypto76

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Very helpful thread, I agree it deserves a sticky. Also, does anyone know the maximum size the bgm.bcstm file can be? It seems that once it gets a certain size it refuses to be added.
 

tyons

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lol guys, it has been clearly stated on the first post. there's the exact max length in bytes.
 

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