Will this work?
clamp part @ 40 degrees

Thanks,
I assume that you are meaning to glamp the part so that the suface is perpendicular to the vertical tool.
It will work and will test the code out.

I have been playing around in Autocad 3D, real PITA to place the checkering just so if one dosen't want to  rotate the part.

Meshcam is used to provide pathing to radius the left side, and then once that is done and without moving the piece, the right side
where the checkering will be placed is  machined to a concave face. This is done with an 1/8" RN end mill. Then without moving the piece a point tool is used to scribe in the checkering. Need to remove the bulk as the darn point tool will blunt out or break in a heart beat...

In addition to the button release also need to do checkering on the trigger and grips which are not even modeled yet. Figured i would start with something easy ...HA HA!

RICH

If it was a surface model, I think it would be easier to create the hatching pattern.

And yes clamp the part at a 40 degree angle so you expose the concave recess vertically up.

Most of these patterns are stamped or pressed in production.

Think Rhino surface modeling would be the way to go. Then project or wrap a line to a surface so you can machine/drive a cutter to it.

Then on the trigger you could cut perpendicular to the surface, and rotate the part on the 4th axis in a temporary fixture.
 

Rich, I looked at the cylinder release on a 625, I believe it is the same frame, the checkering on mine s 90 degree and the concave is a 1/2" radius. If I wanted to model it in 1/3 scale I would make a sawblade with a tooth radius of .166 and stone the edge to the checkering angle. After finishing the shape with a .3125 mill, orient the release for the checkering angle and incremental feed to the depth in X, then Z down and do it again. The depth of cut might need to be adjusted, but the lower half would be a mirror of the upper half with less X as the tool left the horizontal centerline.
Anyway, neat project.

Thanks sandcrab,
That's another way of dong it and the concave on mine is also 1/2" R. I'm trying make all the parts without any manual machining.
Just part of the challenge and forces one to explore. I have hand checkered manny hand grips and rifle stocks but plan on doing the trigger and grip checkering  with CNC. I know for a fact that my checkering tools are not going to be work when the spacing is only .013" or less.
Still have a few things I want to try. Good thing is that the piece is small ...can make it from   3/8" dia round / about 1/8" deep
and a piece of round 12" long provides for a lot of cheap scrap pieces.
RICH

Wanted to try out some code so attached are a few pic's. Was curious as to how the mill would do. Cut the profile of the release button by mistake at 30 IPM instead of 3 ....before I
had a chance to blink  it was done.    Need to play around with the 3d code as I am not happy with the surface finish in some spots.

RICH

One piece down and a bunch to go. One would think that all would be easy but between the code modifications and my
high speed spindle requiring a new collet it just takes a little longer than I thought. So used the slow speed of the mill to do the piece.
Surface finish suffers greatly  but at least it's easy now to duplicate the part. Holding a thou and will be interesting to see how parts fit later.
Here are a few pic's.
RICH

Nice work there, Rich-

Dave