I need to make tortoise shell sunglasses as an accessory to a beach bag cake. Does anyone have any thoughts on how to do this from gumpaste/fondant? Or does anyone have pics of glasses they've done? Mostly trying to figure out how to make the tortoise shell look on them...

I think I'd tint small batches of fondant in different shades of tan and brown, and then mix them like marbling. And then mold the glasses from the marbled fondant. The lenses could be made from the darkest brown color alone.

tortoise shell is a very popular thing for faux finish painters to do. If you google "faux finish tortoise shell" you'll get all kinds of how-to pages for painters. Just apply the same technique using food color gels instead of paint.