Start with a Funko Legacy power armor figure, cut off the shoulder and knee armor, and take off the backpack pieces. Carefully carve off the sideplates off the knees, glue back on, hiding the cuts by using them as the anchor point for glue, and by painting over the bare plastic to match. Kitbashed the backpack, and armor attachment points out of geometric shapes mostly, (may put on thingiverse at request)I gave him a riot shotgun (that I just made a lil sturdier from a thingiverse file) but you can give him whatever weapon you think the figure's crappy hands can hold... Paint and clear coat, and you're done.