How to add a new matter for physics in blender ? (aluminium, titanium etc.) I couldnt find a way to add matters to blender. I need it for calculating object mass. When i do calculate the mass, blender appears me some options to set the matter (iron, brass etc.) and of course there is a &quot;custom&quot; option. How can add my &quot;custom&quot; matter to that list? I dont want to choose custom every single time i do calculate...

As you can see, there is a matter list that comes with blender. I wanna add my custom matters to that list. So i'll be able to select my own matter quickly...
Extra menu script.
AFAIK there is no simple way to tack extra material / density pairs to the operator enum. It is however quite simple, via scripting,  to add a menu of extra options.

Quick slap together proof of concept using Templates &gt; Python &gt; UI Menu Simple  Material &quot;Foo&quot; has density 12.0, &quot;Bar&quot; 0.01,  etc.
import bpy

extra_mats = (
    (&quot;Foo&quot;, 12.0),
    (&quot;Bar&quot;, 0.01),
    (&quot;Goo&quot;, 11),
    )
class SimpleCustomMenu(bpy.types.Menu):
    bl_label = &quot;Extras&quot;
    bl_idname = &quot;OBJECT_MT_simple_custom_menu&quot;

    def draw(self, context):
        layout = self.layout
        for name, p in extra_mats:
            op = layout.operator(
                &quot;rigidbody.mass_calculate&quot;, 
                text=f&quot;{name} ({p})&quot;
                )
            op.density = p
            op.material = &quot;Custom&quot;
        

def draw_menu(self, context):
    row = self.layout.row()
    row.operator(&quot;rigidbody.mass_calculate&quot;)
    row.menu(SimpleCustomMenu.bl_idname)
    
def register():
    bpy.utils.register_class(SimpleCustomMenu)
    bpy.types.PHYSICS_PT_rigid_body_settings.prepend(draw_menu)


def unregister():
    bpy.utils.unregister_class(SimpleCustomMenu)
    bpy.types.PHYSICS_PT_rigid_body_settings.remove(draw_menu)

if __name__ == &quot;__main__&quot;:
    register()

    # The menu can also be called from scripts
    bpy.ops.wm.call_menu(name=SimpleCustomMenu.bl_idname)