Sorry divide the total circumference by 8 then work each eighth one at a time constantly pushing one way like your making a thousand little wrinkles practice on scrap with the same radius and length of one eighth leave some extra to hold on to.
No notches skive the edge just a bit half inch or so then ease the edge by fourths or eigthly one at at a time and that will give you a nice clean edge try a scrap rad first hope this helps.
Chief when i first got my cobra the wife said i have never seen someone sew that much and make nothing ya well when you make that hole in leather its there but all is good now. HA HA . By the way good luck with that new machine looking forward to see more.
You can also ad a filler between the fold like with a knife sheath that should give a little less stress at the BTM when you fold it glue fold stitch then mold.
WoW! Did you make the knife 2 that's some very nice work what steel did you use on the knife . I made a similar one in length it's around 18'' overall with a leather handle and still need to make sheath for it and seeing yours really has got me thinking . Thanks so much for showing it.
Just remember it's you buying the machine with an interest free loan and that's ok as long as you and your friend understand it could take years to pay him back, but all that aside COBRA 4 WITH E.P.S. I have one myself good luck and have fun!
In the book bluesteel&gunleather page 224&225 John Bianchi on custom holsters " The myth of Custom Made" Written as only the world's Foremost Authority on holsters could tell it!.