I learnt of the Trencher smoke wall from the tactica in the Cygnar section of PP's forums. It is such a great way to protect my caster and support solos.
Most templates I have found don't overlap very well especially once models start moving around in the area.
I found these in the file download section of the forums and printed them out. The link to the thread I got them from is here
I figured I better check that they printed out the correct size
I glued them onto thin cardboard to make them a little sturdier and covered them in sticky back plastic to stop them from fraying.
And here they are lined up in the smoke wall formation
A min unit of Trenchers can block line of sight to 10.5" with only the models on each end as viable targets for charges or ranged attacks. You could spread out further but it would not protect the unit from charges as well.
(Worth mentioning never try this against Legion, eyeless sight sees right through this plan)