The pieces are buffed. The reflection looks wavier than it really is.
I cut two sections of 1/8" 416 stainless steel round stock and chamfer the ends. These are polished with 220 grit sand paper so that no scale is on the surface. This is key as the scale on the outside of the pin will show itself as a black ring in the bolster.
The bolster pieces and pins are cleaned and fitted together, then taken to the press for squashing. I have made some flat bar stock with slots. These allow the pins to just squeeze when a large pressure is compressing the bolster. This process sets the bolster, but the pins are not fully compressed yet. I then remove the slotted spacers and finish the pressing.