Closest metric size to 1/16" (for the pins) is 2.5mm (M2.5) diameter. Best place I've found for brass rods is a model shop that does trains.
I've seen M3 bolts and nuts in the remote controlled aircraft sections of some.
It's also worth looking at dolls house accessories (if model/toy shop has any)...I found a few sets of screw head bolts that came with washers that fit 1/16" rod.