Boltaron is even easier to work with than Kydex, at least according to my process. Here is how I make Kydex sheaths.
1. preheat pancake griddle to 330ish, which goes faster when it is covered with a lid (I use a flat piece of rectangular scrap wood slightly larger in area than the griddle). I also use a baking sheet so that I never have to spend any time cleaning the griddle, though I do not use the griddle for food, ever.
2. place two pieces of Kydex on the baking sheet, and cover the griddle so the heat is trapped inside and the pieces come up to temp faster than if they were exposed to the outside air (my shop is outdoors and I do this in Canadian winters, so this is kind of helpful in times like that)
3. remove lid, place piece number one on the press, position knife, place piece number two, and press. That's it. After that is drilling and shaping time.
Here's the kicker: Before I decided to try Boltaron, I read this very thread seeking the wisdom of the knife and sheath sages, whether it be a worthy cause. Forearmed with the knowledge that Boltaron requires a higher temp, I took the plunge, and followed my exact process outlined above, with the exception of temperature, which I raised to 365.
I did two sheaths in the same session, and here is what I noticed: The first two pieces, for sheath number one, looked like black lasagna noodles when I lifted my lid. Oh no! Well, it's still floppy, so I better just get this over with and see what happens. I have a four foot piece of the stuff now after all, so mistakes are planned for. After the pieces were pressed and allowed to cool, I noticed no evidence of the curling, and instead was pleasantly surprised by some of the best definition I had ever produced on a sheath. Oh boy! So far, the process is identical in terms of time (the few seconds to raise the griddle from 330 to 365 are negligible, and I use that time to cover the blades for molding), and outcome, if not better for outcome.
Okay, but how is Boltaron to shape? Here is where it blows Kydex out of the water. My supposition is the higher tolerance to heat is the reason for this. Boltaron, when I grind it on my worn coarse zirconia belts, leaves a fine dust in its wake, whereas Kydex wants to melt and create burrs, if that's what you'd call them. So while I am shaping Kydex, before I switch to the fine belt, I have to take the two halves apart and use my trusty modified Spyderco Resilience wharncliffe to deburr the holes, and a large portion of the outer edge of the sheath. Sometimes there is so much melted and rehardened Kydex gunk that I have to cut for a good couple minutes before it is all gone. Only once all this debris is removed will I put the two halves back together with temporary eyelets and refine the edges with the fine belt. With Boltaron, this doesn't happen. Fine dust, no gunk. If I had to make an analogy of sheath material to blade material, in terms of how it feels to work it, I would say Kydex is like annealed steel, and Boltaron is like hardened steel.
So I am firmly in the Boltaron camp now, after only having made two sheaths out of it, and experiencing fantastic results. I still have Kydex in stock, though, and also Boltaron doesn't seem to be available in as many colors, so for the time being at least, Boltaron is going to be reserved for custom orders, and the ones I make and offer are going to get Kydex. In general. But I'll be investing more into Boltaron as time and cash flow allow.
I hope this thread continues to help anyone who may be thinking about taking the plunge to Boltaron, as it did for me.
ETA: Almost two years later (January 2022), and Boltaron has proven itself to be every bit as good as I was hoping for, and is now my primary sheath material, with the only exceptions being when a different color or pattern is needed aside from black.