I know you should be careful when you say this is the largest case as I said it a few weeks ago when I made a case with a 25 mm internal size.
The smallest of these two cases needs to hold a pen with a 25 mm diameter the largest being 27 mm diameter. Which makes them both larger the the previous record holder.
Fortunately I had some 30 mm dowel which I use to help me form the tops of normal size cases and some 28 mm dowel for the smaller case. There were some calculations to get the right diameter dowel oh and quite a bit of sanding more of that later.
After some more sanding a rounded end and next to a Montblanc 149 for a size comparison
A flat sheet of kydex and large dowels add some heat and a scrap of leather to form the hot kydex.
And here you have kydex tubes waiting to have their ends rounded off.
After rounding the ends of the tubes I cut some strips of suede and sewed up one end and wrapped the whole tube.
The red one at the top of the picture still needed trimming to fit only about 5 mm of this will be seen but I know it has been done right.
Now the inserts are ready it is time to look at the outer cover 2 mm shoulder leather is my proffered leather for cases I cut four pieces two for each case. I soaked them in water for about 30 mins and formed them around the kydex tubes which I had wrapped in shrink wrap to keep them clean and dry.
Sorry the black does not photograph very well.
When I was happy with the shape I got my glue pot out and applied some glue to the lower part and popped the top parts into a zip lock bag. After a few minutes I placed the lower part into its cover and applied pressure with my clamp. Then set them aside to dry
Here are the toggles for these two cases they are carved from oak which has been soaked in a solution of white vinegar with steel wool dissolved in it. leatherworkers call this vinegaroon it reacts with the tannins in oak and leather which turns black woodworkers call it ebonising. (If you make this yourself do not seal the jar as gasses are produced )
Sorry the picture is so bad
Pre assembly pictures
Thanks for looking