When I use paracord for slings, I go with the cheap route of cutting it and then melting the end with a BIC lighter.  For 550 I have the timing down pretty good.  You hit the end with the flame, give it a brief moment, then grab it with your fingers to remold as desired.

I'm working on a couple slings now with 425.  Wow!  This stuff seems to be way hotter.  I learned really quickly that the timing for 425 isn't the same as 550.  I've got a couple annoying burns on my index finger.    But after melting more than 20 ends, I still don't seem to have the timing figured out as well as with 550 cord.

The 'Subject' of this topic was just a joke.  I think the real problem is the 425 cord has less material.  So there is a shorter amount of time between burning your fingers and still being able to manipulate the melted end.  Too short of a time for me so far.

I think that's my first rant on paracord. 

I've never done this. At least not more than a dozen times.

I wish there was a little handheld one.  Maybe that could run off a 9V battery.  Although I would guess that might not be enough power to work well.  And something that small may not hold up over time.

Good call on a rechargeable battery.  That's a way better idea.

I would be curious to see what you can come up with.  I'm not sure what you'd be looking for in a trade, but I'll shoot you a PM.

Well... there’s no time like the present, so I decided to see how hard a handheld version would be to build. I did a really fast, absolutely horrendous proof-of-concept version using trash. When I say trash, I mean it literally...

The abomination pictured here is made from a broken flashlight, an old toilet paper roll holder, and the spring steel from a windshield wiper blade.  When you pull the plunger, it short-circuits a lithium battery through the heating wire.  If you let go, it turns off.  It’s not too terribly unsafe, but nevertheless it still probably belongs with Morphy’s boots at the bottom of a volcano. I learned what I wanted to learn from this monstrosity though: With even a half-hearted effort, a proper handheld paracord hot knife should be fairly simple to build... but it would also really help to have a lathe.

Now it’s time to work on an actual design