For a while now, I’ve been experimenting with different gelling agents. In the beginning, my hope was to use agar agar flakes. But, in my hands, the flakes are not suited to make something resembling Jell-O. I tend to see them used in recipes for panna cottas, mousses and the like. I could never achieve a desirable consistency with fruit juice; either the results were way too stiff or not stiff enough. Also, agar agar is a little too expensive for my taste at $7.50 for one ounce.
Next I tried a vegan Natural Desserts Jel. It’s also a little pricey, but not as bad as agar agar. It’s also a lot more likely to clump as it sets very quickly. But once I got the hang of it, it became my friend. The trick is to heat the liquid, transfer it to a bowl and add the powder slowly while stirring vigorously.
Lastly, I used Knox Gelatine. If you don’t mind the ground up “connective tissue” and other nasty bits that gelatin is made of, this is the easiest and cheapest way to go. I’ve read that one should avoid boiling gelatin, so always soak it in a small amount of coldish liquid, heat the remaining liquid and stir for a good long time until all of the powder is dissolved.