Sniper's C Mk.1 Tripod Pouch [BAM191] - $85.00 : Broad Arrow Militaria
Here is one that sold a few years ago on a millitaria site. $85.....I suspect it would not have been there for long.
They would be easy to replicate.....the same vintage canvas could be salvaged form tent peg bags....I have a number of those in new condition.