They'll be 11 x 17 in color prints on heavy high-gloss 100# poster stock.
If you wish to get copies directly from our supplier, we use OvernightPrints.com. Their cost is about $2 per unit (plus shipping) in quantities over 50. You can get as few as a single copy, but the cost goes up on a sliding scale in lower quantities.
Another good alternative is FedEx Office™, where you can upload your file and order color copies online.
The cost for these in 11 x 17 inch is $1.78 each on standard 24# copy paper or $2.48 each on #90 cardstock (about the weight of poster board).
It's available as a 300 dpi print-quality PDF in 11 x 17 inch and 8 1/2 x 11 inch, as well as in 72 dpi web-quality versions in both sizes.
Please respect that you legally can't alter any part of this poster without the explicit permission of gunfreespaces.org.In the right column, you'll find links to companies that sell similar signage. We're providing them here in case you wish to use a different design to accomplish the same purpose.