Originally, I thought that using the piece of food you wanted to display, + at least one bottle would be the way to go.
(Idea being, you melted the plastic over the pizza or pie you wanted to show off. A bit like the folks on YouTube that put food into resin lol.)
Figured it would be fairer, though not necessarily more 'realistic'.

I picked water bottles because 'empty orange soda bottle' is being used by the bow mod I'm using (you can make fletching from them) and because there is often empty water bottles in trash. (All over lol, if like me, you use the 'trash and corpses' mod) and I didn't want it to conflict (and I don't have many mods that use the water bottle tbh)

Perhaps we can use other materials to craft with (if using the water bottle is an issue?)

For example... Papier mache made from newspaper and glue. Or home made paper clay using toilet paper and glue. Soulfilcher has clay in the 'awesome mod' compilation, but I wouldn't want to add a dependency for that mod to this one....

So...I'd say an empty bucket, a bottle of glue or wood glue and one or two newspaper (or more, depending on how much product you get afterwards) would give you a 'bucket of paper mache' item that could make 3 or 4 larger items.
A bucket of water with say, 10 toilet rolls or 30 tissues? (Not sure, maybe an empty bucket and 1 water bottle instead?) Plus a bottle of glue/wood glue for 'home made paper clay'

Could always use twigs and wood scraps too, just mash em up in a pestle n mortar to make 'sawdust' and mix that with glue/wood glue and tissues/toilet roll/newspaper.

Ultimately, its up to you, I'm just happy to have all this sweet stuff to decorate with 😊

Thanks for the suggestions, I like the paper mache idea and sawdust idea. I think I'll try to implement this :)