Structure: Rules vary from jurisdiction to jurisdiction, but many cities restrict the size of wood stakes to 1/4 inch thick lathe so any structural material can't be used as a club (and can't hold anything large enough to dominate TV coverage).

Material: Use plastic or cardboard stock recycled from industrial discards.

Paint: If you paint on plastic, use a paint that doesn't wash off easily. Paint pens, available at art stores, are much better than brushes or markers. Gold, silver, copper and yellow are available to make the finished signs shine in the dark. A good color scheme is red and blue paint on white stock with gold trim surrounding each letter. (red denouncing terrorism, blue promoting liberty, in the golden state...) Any dark color that you can get from the "oops paint" aisle is okay for protest signs and can be made more visible with the gold or yellow trim.

Weatherproofing: After making signs on card stock, cardboard, etc. you can use a spray can of clear lacquer auto paint to weatherproof it. Laminating is better, but expensive. You can carefully wrap it all in clear tape or shrink wrap plastic, but this does not protect it from fog or other high humidity conditions for long.

Strategy: Use different background colors and put different messages on each side so that when you rotate or flip the sign, it attracts attention. For example: "Rapists love disarmed victims" on one side and "Tyrants love disarmed peasants" on the other. Have multiple people hold a series of separate signs that when placed adjacent to each other read as one. Rotating the signs in unison to a chant really grabs attention.

Construction: Staple first side to stake. Flip. Staple or tape edges of second side to first side. Staple second side to stake.

Options: Attach small flags or flashy wind turbines to your signs if it's windy. Attach helium-filled balloons, or use balloons to lift your sign above all others if it's not.