Size advise requested for making my first leather sheath

[knoefz]

After reading and watching youtube tutorials for a while I'm trying to built my first leather sheath from scratch.
I've drawn a CAD model of the design I want and the contour of the knife (a Markman Taurus12) that I want to fit inside (not my picture that's linked).
Unfortunately I have no clue how tight or how much extra space I should leave around the knife for a nice fit.
I really hope someone experienced here can give me some advice on this.
Here's a screenshot of my drawing:

On the left you see the front (and rear layer), on the right the middle layer of the sheath.
Will this work or will the knife have to much space inside now?
The middle layer has a width of 10 mm (~3/8"), that should give you a size reference.

Also I want to cut the leather on a laser cutter.
Any advice on how to proceed with this to prevent me from rookie mistakes will be appreciated alot.
The leather I have for this is about 3mm thick.

 

[sheathmaker]

Depending on the thickness of the handle what you have designed should work out very nicely. I personally have a standard of 1/2" (13mm) width for my welts. This leaves enough for some loss when squaring up the edges prior to stitching. You 3mm leather is on the low side of acceptable for the purpose, but may work out just fine. If your handle is bulky you may need to install a tapered wedge on each side of the welt down about 10 holes as you have drawn it to increase the mouth opening without making the sheath wider.

Paul

 

[knoefz]

Thanks for your input Paul.
The leather wedges make sense.
I'll see if how far I come.

It'll be a while before I get this started but I'll make sure to post some pics on the forums when I have some results