First off sorry for the bad quality photos my camera wasn't great but anyway have you wanted to charge your 3ds (or any device that works with the charger) with a computer. Just make sure you have an extra outlet one and get started

Step 1: Materials

Just have a 3ds charger and a usb charger for 5 volts (most phone chargers are)

Step 2: Open the Cables

I couldn't get good photos for this one but all you need to do is open the cords so you can see the wires. The 3ds on keep the copper on the outside and the one wire with plastic exposed

Step 3: Attatch

put the red wire from the usb charger to the wire (with plastic) on the 3ds one. twisting together is enough. Then put the black wire to the wire outside of the plastic one. twist those together too.