LDS (Low Density Structure) by Molten Plastic recipe does not work in Foundry.
The recipe appears but its red and when clicked on it says "cannot be crafted in this machine".

Hey there,

thanks for you report, this is not a bug.

The foundry only has two fluid inputs while the recipe needs three; It's mostly there for other mods that add advanced foundries such as Age of Production or my Casting plant mod. There is however a recipe with solid copper and iron using molten plastic that can be used in the foundry.