1-Make Cylinder as you like with the dimension put edit poly on it try to increase segments to be squared
2-Remove the top/bottom faces and put turbosmooth on our cylinder
3- Select all faces in the cylinder and make tessellate don’t put any numbers just leave the command doing the job for you it will give you similar result as in image down below
5- Select the vertex and make extrude as in image down
6- invert the vertex selection and scale it out don’t select the top & bottom vertex
7- Select the edges and make extrude as in image down
8- active the turbosmooth with iteration 2 or as you like for your model
9- Thank you
