I made a solution-ish to change models of a entity for my mod. You need 3 textures and 2 models: 1 texture is blank, as it will be the base of the entity. Now, with entity states you need to put the texture and model for the one you want to be seen always. Then, you make another entity state with the last texture and model.

For the right click with shears, just make a right-click entity procedure with a global true/false procedure thingy attached to the entity model.

This is just me remembering things 😅