The head sculpt is a Hot Toys Taxi Driver head , prior the shaving his mohawk ... Or is it Mel Gibson ... ?
Anyway...

"Civilian" camera/safari vest is made from a Viet Nam jacket , sans sleeves.

Scarf is made by first creating an Adobe Illustrator document with scarf pattern , then starching and ironing gause fabric and finally printing
the gause in an HP inkjet printer.

I find that most of the scarves available are too stiff either due to fabric or the plastisol silkscreen ink the manufacturers have used.

The combat sling on his weapon is custom made as well. I have some SF buddies and this is how they make theirs.

The sand / dust is applied by first spraying MATTE clear enamel on the desired area , then brushing on the dust left over from inscence .