Paracord is a lightweight yet strong cord that was originally developed in the military for (you guessed it) parachute riggings but is now used in a lot of DIY projects many of them centered around weaving the cord into bracelets, lanyards, and carry straps. If you want to attempt one of these projects make your life easier by temporarily adding a small nail to simplify knot tying.
Tactical weblog Imminent Threat Solutions points out that temporarily adding a small nail fused into the end of the working end of your paracord serves to help move the end of the cord through a difficult knot head and untie knots just like a marlinspike does in traditional sailing rigging. Once you've cut your paracord for your project insert the head of the nail into the cut end of your paracord and use a lighter to temporarily fuse the nail into the cord. When you're done you just need to cut out the melted plastic tip of the cord holding the nail and fuse the paracord end together again.
Reader Tip for Difficult Paracord Projects [ITS Tactial]