I do a glitter shell (clear plastic, or just a drop or two of black per cup to make the glitter stand out more without clouding the plastic much) with a blood-red core. I will sometimes use a red colorshift if it's a coreshot worm with a tail (I forget the name of the mold, AnglingAI makes it). Lots of variations with that using different glitters. I typically use the finest I can get with a fancy-sounding holographic name. "Laser Diamond Holographic Silver"? I mean, sure.
Copper or gold pearl veins in a smoky shell work nicely, especially if you cut the tip so the tail end fills in with the core color.
Fun trick to use when your cores don't completely fill for whatever reason - take out your tube slitters and make yourself a fancy solid-body tube wherever the core stops. It won't be perfect, but it's usually fishable.