Flintr - The sight has an iron base, with steel blade and 1/8" or smaller rod of brass soldered to it, on a sloping angle, the top being towards the rear. This bead is filed off square, so any light it picks up, is flat and it shows the true position of the bead. If the edges are rounded, they'll highlight and will definitely throw shots with varying light conditions.
I notch the angled flat of the blade with a fine needle file so the short bead rod sits in it without you touching it. Both are finely tinned, with flux. They are set on a brick (fire brick preferred) and head applied to the bottom edge of the base, bringing up the temp until the solder flows. When cool, the base is clamped in a vice, and the bead is filed to a tapered angle, large to small at the lower end.
I have also used other materials for the sight, but of course, they are best if of one piece, except for the bead - ie: only one solder joint. I use low contend silver electrical solder, low melting point and it holds just fine. I've also used 50/50, 30/70 tin/lead(or visa/vis) solders and they all work.