I did it by roto-ing the original bolts themselves with a mask in After Effects, duplicated, and blurred the masks in 2 or 3 varying radius layers. This way the original shape is preserved, and you have explicit control over the core/glow percentage. There was no workable template; each bolt needed basically a different setting for each frame. Like everything else in Legacy Edition, it's 99% roto. But you can't beat the quality.