The Fretz Spinner Ring Set is made up of 2 components. First the concave curved stamping mandrel, SRM-1, which is used to flare the bands edge, one side at a time, and then the two hole faced steel block, SRB-1, which is used to support the ring and let the mandrel pass through the ring as it is being flared with a stamping hammer.
To make a 2 piece spinner ring, place your wider ring on the concave curved stamping mandrel and hammer the mandrel's end to gently flare one side of the ring. Count the blows so the other side can be done with the same force to maintain symmetry. Then place the narrower "spinner ring" over the non-flared end of the wider band and repeat the flaring process (using the same amount of blows you did for the first side) to lock the "spinner ring" on.