Often I want to watch with my son something on my laptop, smart phone or tablet. Usually, such devices have only one plug for earphones! It's curable with 3.5 mm audio splitter. Sure, you can buy it at online stores for just a couple of dollars. Or you can make it yourself if you have spare 15 minutes plus necessary parts: audio cable with male connector (I got one from broken earphones) and female audio connector (I salvage it from old broken PC). This particular female audio connector has 2 plugs.
In this video instruction you will see how to put it all together to make audio splitter.
This video was recorded and edited with the help of my six years old son Eric for our special project.
Blog: http://rndmbits.blogspot.com/2015/05/audio-splitter-diy-how-to-make-35-mm.html
More fun on my website www.fewdoit.com