Drop this in editor/Python/plugins/csSimBrush/startup.py

startup.py

# @author Chris Sprance
# @Description Open the window from Tools->csTools->csSimBrush
# select a brush and click Convert Brush To SimBrush and it will sim and fall
# Move the object and press simulate again to simualte again
# Click Convert SimBrush to Brush to convert the selected simBrush back to a regular brush


from CrySide import QtWidgets
import SandboxBridge
from sandbox import general
from sandbox import physics
from sandbox import ui_action


class CsSimBrushWindow(QtWidgets.QWidget):
    def __init__(self):
        super(CsSimBrushWindow, self).__init__()

        self.setLayout(QtWidgets.QVBoxLayout())

        brushSim = QtWidgets.QPushButton("Convert Brush to SimBrush")
        brushSim.clicked.connect(self.simobj)
        self.layout().addWidget(brushSim)

        simMore = QtWidgets.QPushButton("Simulate Again")
        simMore.clicked.connect(self.simmore)
        self.layout().addWidget(simMore)

        simBrush = QtWidgets.QPushButton("Convert SimBrush to Brush")
        simBrush.clicked.connect(self.setobj)
        self.layout().addWidget(simBrush)

    def simmore(self):
        physics.simulate_selection()

    def simobj(self):
        self.objname = general.get_names_of_selected_objects()
        objpos = general.get_position(self.objname[0])
        objrot = general.get_rotation(self.objname[0])
        objscale = general.get_scale(self.objname[0])
        self.physobj = general.new_object(
            'Entity', r'RigidBodyEx', r'brush_sim_temp', 0, 0, 0)
        # set the physobj to be the selected brush object
        sel_name = str(general.get_entity_geometry_file(self.objname[0]))
        # general.set_entity_property('brush_sim_temp', 'Model',sel_name)
        general.set_entity_geometry_file('brush_sim_temp', sel_name)
        #     3. snap physobj to xform of selected object
        general.set_position(self.physobj, int(objpos[0]),
                             int(objpos[1]), int(objpos[2]))
        general.set_rotation(self.physobj, int(objrot[0]),
                             int(objrot[1]), int(objrot[2]))
        general.set_scale(self.physobj, int(objscale[0]),
                          int(objscale[1]), int(objscale[2]))
        general.set_entity_property(self.physobj, r'Mass', 45)
        general.log('hiding ' + self.objname[0])
        general.hide_object(self.objname[0])
        general.select_object(self.physobj)
        ui_action.actionPhysics_Simulate_Objects()
        general.clear_selection()
        general.select_object(self.objname[0])

    def setobj(self):
        physics.get_state(self.physobj)
        physpos = general.get_position(self.physobj)
        physrot = general.get_rotation(self.physobj)
        physscale = general.get_scale(self.physobj)
        general.unhide_object(self.objname[0])
        general.set_position(self.objname[0],
                             physpos[0], physpos[1], physpos[2])
        general.set_rotation(self.objname[0],
                             physrot[0], physrot[1], physrot[2])
        general.set_scale(self.objname[0],
                          physscale[0], physscale[1], physscale[2])
        general.delete_object(self.physobj)


SandboxBridge.register_window(
    CsSimBrushWindow, "csSimBrush", category="csTools",
    needs_menu_item=True, menu_path="csTools",
    unique=False)