How do you make Welch's fruit snacks?
This, I confess, is just a guess—I'd suggest adding some pectin.

Pectin is a thickener that occurs naturally in fruit, but its likely absent entirely in the fruit juice you've been using. However, it's probably present in the fruit purée used in the commercial products.

Pectin is, for example, the primary (if not only) jelling agent in jam, jelly, and preserves. In the store, Sure-Jell and Certo are common brands.

I'd try to get HM pectin (the one that isn't sold as "low sugar") to set first. It'll probably provide a firmer fruit snack. LM pectin may work, too, if you don't have enough sugar (I doubt insufficient acidity will be an issue).

I suggest, as an alternative to ice cube trays, use cornstarch molding. Basically, you press an indentation into cornstarch, and then pour the stuff in. Let it cool &amp; dry in the cornstarch. Then remove the cornstarch. You can re-use the dry part of the cornstarch. This will deal with the stickyness, but the finish will be more matte.