Picked this up - was hoping it would be an ftd can, but no - instead an arr42 no Waffenamt can. RGK is unmarked - I think I know the maker but let’s see what’s said to see if I’m right. I think all of the beads are steel.
Saved the pic and subjected it to my Win10 photo edit program. Whatever it is, one can see three pairs of straight lines on the lower part on each side of a indistinct center and they are tapered inwards from top to bottom. Then it looks like two similar, pairs of lines above. Strange location and laid out the way they, appears almost intentional. However, since you have more than just a photo to go by, it must be otherwise. Also noticed the crude file marks on the pictured edge of the patch loop.I think you are seeing tool marks and not a waffenamt on the rgk