小銭を積み重ねたような、コインを積み重ねた

The Whip Stitch Weave is a technique used to produce the "Stack of dimes" effect in welding by solidifying the weld seam in intervals using a front to back movement of the torch along the path of travel. (Weaving in Welding, Weave along Linear, Radial and Stitch weld paths, by Gaurav Shetty)