Mungo and Beast follow similar formulas. I made Beast first, and liked him so much I decided to do another one along the same lines. They’re both essentially Ash Wastes Nomads with 3rd party mutie heads, arms and weapons (IOL minis).
The only thing I did to Beast was cut away the pistol in the holster and add the handle and tip of an Untamed Beasts knife in its place, along with a Kroot knife, and add more tattered laced up cloth to his left arm.
The hobby session where I did this sleeve was when I really cracked how to make this laced up cloth. First I sculpted the shape of the cloth, then using a scalpel I put the line into the green stuff where two parts of the cloth meet. Next I rolled a very thin sausage of green stuff, about 0.25mm thick, and cut several lengths of it 2-3mm long. Finally with a pin I picked up each length of lace in turn, by the tip of the length, and poke it into the cloth on each side of the line. The pin secures the lace in place and creates the stitch holes at the same time.
Mungo was a bit more involved. To differentiate him a bit more from Beast I cut off the lower legs from the Ash Wastes Nomad and replaced them with some cut from a Pox Walker, blended in with putty.
The right arm and shotgun are IOL minis and the left arm is Kroot. The head is a Plaguebearer head. The backpack is Nomads but combined with some random mechanical looking part from the bits box and lots of added baggage from Kroot, AdMech and Marine kits.
I went to town with the laced up cloth here, adding some to the left leg, left sleeve and the bulging bag hanging from his waste.