Mice 004 - How to Seal a Small Opening

I've discussed holes around penetrations such as air conditioning lines and drainage pipes, but here is how I approach actually sealing such issues without permanently modifying the structure. Again, I do not recommend permanent or semi-permanent solutions such as caulk and spray foam for this purpose unless there is no other choice or regulations require their specific use. They are notoriously difficult to remove when the time arrives to replace them due to wear from the sun and elements. Generally, most pest control technicians do not do this sort of work as it is outside the scope of what they are trained and insured for. I'm just too nice of a guy, and it'll probably get me in trouble some day.