The guides below can't be used to stream DS games, DSiWare, and GBA games. You will need a hardware capture card to do that.
This page will show you how to stream your 3DS console's screens to your computer over WiFi. For both methods, keep the following things in mind;
Your console and your computer need to be on the same network.
Streaming audio over WiFi currently isn't possible, you will need to use an AUX cable and a device with Line In to receive audio.
If you have a poor connection, you may not get the best results.
While you shouldn't stream from an Old 3DS console due to the very low frames you will get, the section is still here as a 'proof of concept' thing that you can mess around with. It is not intended for practical use.
Finding your Console's IP
You'll need to know the local IP address of your 3DS later, so it's a good idea to find it now.
Start the Homebrew Launcher
Press Y
Launch FBI
Select "Remote Install"
Select "Receive URLs over the network"
Open Rosalina with Left Shoulder+↓+Select
Select "Debugger options..."
Select "Enable debugger"
Press B to continue
Find the IP address in the top right corner
Recommended: Select "Disable debugger"
Streaming with NTR+Snickerstream (recommended)
This method is not possible with Old 3DS models. You will need to follow the HzMod guide below.