I like a lot to use mylar (polyester heat resistance) film inside my poured soft baits, but more funny is to place fin shaped pcs of mylar on the external side of soft baits, to do it I put a little bit of paper glue in stick over the fin and position it on each side of the mold, after that you can pour or inject. The result is a shining detail over the surface of soft bait.
I usually find mylar holographic foils in Fly Fishing Shops, as Flashabou Mirage of Hedron or ShellBack of Hends.
Another realistic system is the Myalr Net, sold as pipes, but please don't use it as a closed insert (ex. Berkley Soft Bait), because every time you place a hook with barb, then you nail the net pipe and every time you remove it: cut it for its length and position the net over the internal sides of the mold as above described, you will obtain a real fish skin texture.
Just my two cents.