GYTB (an acronym for Give You This Budge) is a homebrew app for the 3DS, developed by MrCheeze. It allows you to install image files as custom badges to display on your HOME Menu. GYTB only works on system firmwares 9.3 and above.
Installation
Power on the console
Open Universal-Updater
Tap the magnifying glass on the bottom screen, then search for GYTB
Press A while hovering over GYTB from the list of homebrew
Choose GYTB.3dsx for the Homebrew Launcher or GYTB.cia for HOME Menu installation
Wait until the app installs
Exit Universal-Updater
You can scan one of the QR codes below to download and install the program using FBI. To do this, start FBI, then go to "Remote Install", then "Scan QR Code".
Copy the 3ds folder from inside the GYTB_hax.zip onto the root of your SD card
If you are using macOS, hold the ⌥ Option key while dragging the folders to the root of your SD card, then click Merge
Badge requirements
Custom badges must be .png(s) whose dimensions are divisible by 64 pixels
Theme Plaza has a large collection of such badge images
If you get custom badges from Theme Plaza, look for and delete preview.png
The custom badge's name is set to whatever the filename of the badge is
Images larger than 64x64 will be split into separate badges (eg. 128x128 will be split into four badges)
Badges split in this way will share the same name or app shortcut
The most badges you can install at a time is 1,000. If you attempt to install more than 1,000 badges, GYTB will crash.
Shortcuts
Custom badges can be made into shortcuts to launch system applications; a list of compatible titles can be found here. To create a badge shortcut, rename the badge so the TIDLow of the system app is between the first and second period of the file name, like so: BadgeName.<TIDLow>.png. For example, a file named settings.00021000.png would create a badge named settings that launches USA System Settings (mset). Badges made into shortcuts will display the banner of the application they launch, rather than being a pin; applications without a banner will display a default banner instead.
Instructions
Section I - Prep work
Create a badges folder on the root of your SD card
Copy your badge .png files to the badges folder
Reinsert your SD card into your console
Section II - Installing Badges
Power on your console and Launch GYTB from the HOME screen
You should see your badges flash on the screen, and be sent back to the HOME Menu afterward
Section I - Prep work
Create a badges folder in the same location as GYTB.3dsx