Up next,"Build this small welding unit using only things you find in your backpack!"

I think Ken did a great job but missed an interesting point, if you have one of these cheap chargers and leave it plugged in with the end laying about on your desk waiting for you to bring your Macbook and plug it in, then anything on your desk can short it. Pen clips, paper clips, metalized trinkets from the last trade show you visited. If you aren't the clean spartan desk type (and I'm not) you may find burn marks on your desk where things have hit the end of the connector, or worse.