Are elven requests random or fixed sets?

[trailbean]

What I mean by this admittedly confusing question:

Here is a recent elven request. Does this combination (mysterious venom, white petals, orange coral, blue petals, tomatoes, enchanted blocks) occur repeatedly, or can any of these items randomly mix with any other items?

[tigarlilyvol]

all can be mixed with other items So it's random, even the same list can eventually be asked for.