Am making an all-vegan wedding cake so am looking for a high ratio shortening that is not made of animal fats. Any ideas?

Sweetex is not made of animal fats. It is made of Soy which is a vegetable.
Sweetex Z is made of Palm oil

Spectrum that you can buy at a health food store or your local organic section is also Vegan, Gluten Free and is made of palm oil.

I don't think I've ever seen shortening that wasn't vegan.

Unfortunately there are some store brands that are not all vegetable. I have never used them, but they are mentioned here on CC.

Walmart sells a few kinds under their brand. I was surprised to see that one of them was animal based. I didn't realize it until after I had gotten it home and used it. My frosting tasted like the fat drippings can my Grandma used to keep on the back of the stove. eck!