Corrugated plastic is a low-cost, recyclable plastic comprised of a wavy, grooved layer sandwiched between two flat sheets, all made of a high impact polypropylene resin. It is lightweight yet durable enough to withstand the outdoor elements, which makes corrugated plastic the ideal material for an indoor or outdoor sign. Corrugated plastic can easily be cut with a craft knife, painted and adhesive lettering may be applied without tools because it has embedded lines that align their placement. Corrugated plastic may be bought from retail companies or businesses may offer used sheets at a low-cost or even for free.
Cut the corrugated plastic sheet with a utility knife or an electric band or scroll saw. Lay the plastic sheet down on a flat hard surface, such as a cutting board or hardware table. If using a utility knife, steady the cut with a ruler or T-square. If using a saw, it is best to use clamps to hold the corrugated plastic down allowing you move the saw blade along the desired cuts.
Paint the corrugated plastic sign. The best paint to use is fusion paint because it is made specifically for plastic. Depending on the size of the sign, one whole can of fusion paint is required to cover both sides of the sign. Apply the first coat of paint and allow to dry completely before attempting to paint over it or the first coat will blister and peel--try to keep the paint job within one hour to prevent damaging underlying layers. Paint the sign while it is laying down horizontal to prevent the paint from running.
Add edging to the corrugated plastic signs. This is an optional step but one that will give the sign a professional look. It can be edged with more paint or colored duct tape. Colored duct tape is sturdy, flexible and adheres to plastic very well. Do not overlap the tape or it will not look smooth like paint, so apply the tape to either the horizontal or vertical edges of the sign all the way to the edge and then apply the tape to the adjacent edges but between the first layers of tape.
Attach adhesive lettering to the corrugated plastic sign. Corrugated plastic has embedded lines that create a grid all across its surface that can be used to align the letters up without a ruler. Decide on what is to be written on a plastic before beginning. Locate a center letter of the phrase and apply it to the sign. Apply the rest of the letters, starting at the center and working outward on either side of the center letter.
Attach metal grommets to the corrugated plastic sign. Grommets, which form reinforced holes through various materials, are used to hang the sign if desired. Create holes through the sign with a grommet tool to where the grommets are to be placed. Attach the metal grommets to each of the holes. Be sure to use grommets that are deep enough to go through both sides of the sign.
Corrugated plastic signs are very durable but, depending on the climate and weather conditions, expected to last approximately three years.