If your looking for a no guns sign for your home or business, you can download a nice one at City of Madison's website.
I thought this comment provided a few other suggestions to get your signs:
And if you'd like to help organize and ask businesses to post signs, contact the Wisconsin Network for Peace and Justice in Madison or Wisconsin Anti-Violence Effort, Veterans for Peace Chapter 102, or Peace Action Wisconsin, all in Milwaukee. They all have signs available in quantity.
