I had a shoelace that was pretty well mangled, and didnt want to run out and buy a new pair. Granted they are usually pretty cheap, but I have a few hundred feet of 550 paracord at home and figured I'd make some quickly. I wanted to also have the stiff finished end (called an aglet) that wasn't just melted paracord. I decided to try heat-shrink tubing. Heat-shrink tubing is supposed to be for electrical connections, but it's incredibly handy for other things as well. The tubing generally comes in 3 sizes. I've seen small medium and large, in black, red, and white respectively. Your mileage may vary :)
27 to 72 inches of paracord for each lace (I made each of mine 60 inches, therefore needed 120 inches)
Automotive Heat shrink tubing, (about 1.5 inches per lace, for 2 laces, 3 inches)
Lighter or match
Step 1: Cut to length
Cut the laces to the desired length. Sometimes the inner cords of the paracord will pull away from the cladding. Cut the end so that they are as flush as you can get them .
Step 2: Aglet
Cut about 3/4" of heat shrink tubing and slide it over the end of the lace. If the cladding bunches up inside the tubing, slide the tubing so that the lace comes all the way out the other end, and then pull the lace back out until the cladding is flush with the end of the tubing.
Using a lighter, apply heat to the end of the tubing. It will shrink tightly around the lace. Remove the heat and quickly roll it between your thumb and index finger to tighten it a little more (this will make it easier to lace your shoe)
Step 3: Enjoy
Lace up your kicks and enjoy the satisfaction of having "made" something durable for yourself instead of wasting time and money getting new ones (that wont last long anyway)