Unlike a lot of kong stuffing recipes which use treats and fattening foods, the bulk of this kong is dog food taken from her dinner to keep her athletic figure. It uses her dog food mixed with some non-fat greek yogurt and unsweetened applesauce and then top it off with pumpkin puree. Pop it in the freezer for several hours and you will have a wonderful food enrichment tool - and an hour of sanity during puppy hood.
This is a great list of homemade dog toy projects, and they range from easy to more difficult. I, personally, wouldn't make anything out of socks, so that your own socks never get confused for a toy, but there are many other great ideas here.