This is how 2 Grampian GR1/L or GR2/L ribbon microphones were re ribboned about 20 years ago. They sound very nice.
The corugations were made before the ribbon stripe was cut.
The few micron thin aluminium foil was held sandwiched between the 2 thin papers. It was then zig zag bent by hand in an accordion shape. Then it was placed flat again and then cut. So the corrugations were already there.
The ribbon was tensioned while listening to the mic (protect your ears) and tension was adjusted for max bass. The resonant frequency must be near sub audio.
Connections to the input transformer were done by same length cables in parallel like antennas, so that any field picked up would cancel. (Even the small length side wire was made long and placed straight along the side of the magnetic circuit structure. So there was geometrical symmetry between the 2 wires).
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