How to Display a 3D Item Model Inside a Tooltip
One of the mod's headline features is rendering an actual rotating 3D model inside the tooltip instead of a flat icon. This is configured through the same resource pack style system that controls colors.
Enabling the Model in a Style
Open the tooltip style file you want to modify. Look for the model or render section — the mod exposes options for whether a model is shown, its scale, and its rotation. Enable the model display flag and set a scale value that fits your tooltip size. If the model is too large it will overflow the tooltip box, so start small and increase gradually.
Pointing the Style at a Model
A style needs to know which model to render. For most items the mod can use the item's own model automatically, but for custom display you can specify a model path. Make sure the referenced model file actually exists in your resource pack, otherwise the tooltip will fall back to a flat icon or show nothing.
Testing and Tuning
Apply the style to a test item, then hover it in-game. Use F3+T to reload resources after each edit. Adjust scale and rotation until the model sits nicely centered. Note that very complex models with many elements can hurt performance when many tooltips are open at once, so keep models reasonably simple for items that appear in large inventories.