These "blood vessels" and "eye muscles" are actually, you guessed it pull and peel licorice.
Try to keep 3 or 4 in a bunch, pull off both ends so that the end loses that blunt look.
Then gently peel apart the top of a bunch.
This piece should be about 2-3" long.
Then gently press this into the gooey candy melts and hold for a bit until it stays put.
Do 3 bunches per eye, and add a few single strands for more detail.