Things You'll Need
Instructions
Draw a shape on a piece of cardboard in the correct size of your billboard according to HO standards. In HO scale, one real life foot equals 3.5 mm. If you want a correctly sized billboard that is, for example, a billboard 20 by 10 feet will be 70 mm long and 35 mm tall in HO terms.
Craft a billboard frame using square extruded plastic ̶0;steel̶1; parts from modeling kits, or square balsa wood. Make the outer frame members to the proper length for the top and bottom rails of the frame. Make numerous inner frame members. Glue these members together; pin them with straight pins for extra strength: snip off the pin heads, flush with the wood, with jeweler̵7;s wire cutters.
Cut a sheet of cardboard, balsa wood, or scrap plastic to fit over the frame. Attach this billboard backing to the frame with glue and more pin ̶0;rivets̶1; if desired.
Cut three strips of narrow plastic or balsa wood to form a scale model ̶0;deck̶1; the same length as your billboard. This ̶0;deck̶1; should be about 14 mm wide. The deck is the boardwalk the billboard worker stands or walks across while hanging a new billboard sign. Connect the three planks together, side by side, on the underside of the planks with cross timbers made of balsa or plastic.
Connect this deck to the billboard frame with cross timbers made of balsa or plastic. Use any bridge or trestles on your train layout as a guide to sensible cross timber construction.
Glue three or four HO model street light fixtures so they can be used to ̶0;light̶1; your billboard. Glue the heads of the light fixtures to poles made from scrap plastic from kit models. Glue the poles to the billboard frame so the light fixtures are angled down on the front billboard surface.
Create a scale model of a billboard advertisement in your computer graphics program. Set the size of the billboard to equal the size of your billboard backing. Print the graphic out, trim it, and glue it to your billboard backing. For a weather-faded look, turn down your printer ink settings.
Glue four balsa or plastic ̶0;telephone poles̶1; onto your HO layout or counter sink them into the table. Space the poles so they can support the billboard assembly. Determine the correct scale placement of the billboard. A typical height would be 20 feet above the ground, or 70 mm. Mount the billboard assembly to the telephone poles with glue.
Create a small rung ladder to scale̵2;about 8.75 mm wide by the correct height̵2;and install it on the billboard structure, either ̶0;down̶1; with an end on the ground, or ̶0;up̶1; with the end of the ladder off the ground.
Paint the scale model billboard to suit using plastic and/or wood modeling paints.
Plant HO scale "tall weeds" or shrubs around the base of the billboard to finish the look.