Quick example publishing a mesh for mesh_tools (https://github.com/uos/mesh_tools)

mesh.py

import numpy as np

import geometry_msgs.msg as geo_msgs
import rospy

import mesh_msgs.msg as mesh_msgs


def publish_mesh(pub):
    mesh = mesh_msgs.TriangleMeshStamped()
    mesh.header.frame_id = '/map'
    mesh.header.stamp = rospy.Time.now()

    vertices = np.array([[0, 0, 0], [2, 0, 0], [0, 3, 0], [0, 0, 1]])
    faces = np.array([[0, 1, 2], [0, 3, 1], [0, 3, 2], [1, 2, 3]])

    mesh.mesh.vertices = [geo_msgs.Point(*v) for v in vertices]
    mesh.mesh.triangles = [mesh_msgs.TriangleIndices(f) for f in faces]
    pub.publish(mesh)


if __name__ == '__main__':
    rospy.init_node('rviz_mesh_test')
    pub = rospy.Publisher('/mesh', mesh_msgs.TriangleMeshStamped, queue_size=1)
    rospy.Timer(rospy.Duration(1), lambda e: publish_mesh(pub))
    rospy.spin()