One of the less enjoyable parts of making gear from synthetic materials, such as ripstop, is cutting the material and then heating/searing the edges to prevent fraying.  I have tried matches (bad idea) and candles (ok but results in uneven edges and requires considerable time and gentle care to avoid a mistake).  Using a fell seam or french seam might obviate the fraying problem but again, requires more effort.

I followed several forum’s on the use of hot-knifes (including those here). Hot knifes can be obtained at fabric stores for ~$45 into the $100s.  I recently came across the discussion on a forum of wood-burning knifes and soldering guns for cutting fabrics.  .. and, now based on my experience, I can attest the soldering iron works well! 

I purchased a $20 Weller (TB100PK) Therma-boost soldering gun in a ‘gun’ format (see pic below).  The soldering gun contains 6 tips, one of which (i.e. the ‘rope cutting’ tip) is perfect for cutting ripstops.
I have used it to cut a variety of lightweight ripstops (the 1.1oz uncoated ripstop in the pic below).  The cut is made by the heat alone (i.e. the tip is really not sharp) and results in a perfectly sealed edge on both sides—straight also.  I have not yet tried the soldering iron on heavier fabrics (e.g. dyneema).

Remember to put scrap glass below the material to cut on and use a metal (e.g. aluminum straight edge).

Just adding a quick note on sources.  Harbor Freight tools is an import tool dealer.  Most of their stuff is sourced from China, and is pretty cheap.  For light usage, all of their tools are excellent. Here’s a couple of items that can be had for < $10:

Hobby Wood Burner for $9.99
Pencil Tip soldering iron for $4.99
Big @$$ pistol grip soldering gun for $9.99

I tried this with a pencil style iron, a low wattage one for soldering small electronics.  I did not get the results you did.  I liked the idea though.  Saved time not having to flame the edges.  Might have to give it another shot with an iron like the one you have there.  That looks like the ticket.

Hi - I’d like to throw my 2-cents in.  I’ve had good luck with the Weller solder station (adjustable temperature) pencil irons.  Use a small conical tip, set the temp to max.  Cuts and seals in one step, is very easy to use.

My first tries were with the temp set to my “normal” soldering temperature.  It wasn’t hot enough.  This makes me think that the low wattage irons with the 2-prong plug that you plug into the wall probably won’t “cut it”  :)

If you can find one of the adjustable temp stations you will have good cutting.  I haven’t tried my old Ungar station yet, but that thing got REAL hot so if I can find a conical tip maybe I won’t have to risk my good electrical soldering iron. 

And the glass working surface is a MUST. 

And added benefit - once you start cutting, the material will tend to stick to the glass so you can pull it tight.  Don’t let it bunch up or the iron will plough a HUGE swath in your expensive material.

You can also free-hand curves by outlining them (I use chalk) and carefully following your pattern.  I’m not particularly good at free-hand, but it usually gets hidden inside a seam so go for it!!

Happy Projecting and Hiking!!