As any of you Chromecast owners will know, when you use the TV as the power supply for your Chromecast, your Chromecast will be on as long as the TV is on. Typically this isn't an issue, but we use an aerial to get our live TV and having the Chromecast on interrupts the signal. This switch was a project I did just so it could be turned off without unplugging it, enjoy.
-Hot glue gun (optional)
-On/On toggle switch
-Chromecast power cable
Step 1: Strip the Cable
Use your wire stripping tool to split the cable that came with the chromecast at two points about an inch apart. Then use an x-acto knife to cut the length of insulation in half and remove it. After that, you'll have to cut/peel off the outer shielding for the cable. Then there will be a bunch of uninsulated wire, this is also the ground so just peel that back until you only have the positive, negative, and ground wire showing. Now cut all three right down the middle, and use a stripper to peel back the insulation so the three wires can be soldered later.
Step 2: Creating the Housing
I just used a project enclosure I bought from radioshack at a clearance price. You can find these online or at your local electronics project store. I drilled two holes on either side for the USB to go through, and one on top for the toggle switch.
Step 3: Soldering
Once you've fed the cable through each side of the enclosure, solder the negative wires together and the ground wires together. Now if you have an on/on toggle switch with three prongs, just solder the two positive wires to any two prongs that are directly beside each other. After this I hot glued everything to prevent a short. I also hot glued where the usb cable enter and exits the enclosure to stop it from being pulled and damaging the switch.
Step 4: Done!
I added a little on/off emblem for ease of use, and the chrome logo from the box. Hope this guide helped :)