I decided to make my own grill mesh to fill in the gaping holes in the rear bumper of my 2012 Cayman R. This is a very simple DIY and I did it in a few hours and for about $50. I think it turned out great.
First, after much google searching and getting real smart on what kind of different mesh materials are available such as perforated, woven, or expanded, plastic, aluminum, steel, brass, etc, I came across the perfect material that I think looks much more finished than the expanded mesh used most often. It is a 0.25″ honeycomb aluminum that comes in a 36″x40″ sheet for about $40. It has 79% airflow, should I ever decide to do the front vents. Its also enough to mesh every vent on the car if I felt like it. It matches the hex pattern in the sport bucket seat headrest exactly. Anyway, I cant say enough good about this company http://www.mcmaster.com/#standard-pe…sheets/=iemba7 for sourcing the material (follow link and scroll down to Hexagon-Hole Perforated Sheets). It shipped the next day and came flat in a huge cardboard envelope.
Make a template:
This was pretty easy, and Ill save you a few trips under the car to start out. Cut a piece of corrugated cardboard from a box to 4″ x 18.5″. You want about .5 of overlap all the way around where the mesh will cover the hole in the bumper. When you look behind the bumper, you will see some small tabs around the holes. These will be what you attach the mesh to. One look behind the bumper and you will see what is involved. Take the rough cut template and place it in position lining it up along the bottom edge and the edge towards the center of the bumper. Draw and then cut the curve on one side so it fits properly. Once the rough shape of the template is complete, carefully hold it in position and press the mounting tabs into the cardboard to make a mark.
Now with a razor blade, cut slots into the template where the tabs made their mark. Test fit the template, making sure the tabs all line up and the size is the way you want it. Once you get the pattern on one side, the left and right sides are symmetrical, so only one template is required.
Now draw the pattern on the aluminum mesh: Line up the bottom of the template with the bottom edge of the mesh to keep the holes aligned and level (though I dont think you could tell the difference if they werent, but it would drive me nuts knowing). Cut the mesh with metal shears. You may be able to use a good set of regular scissors, but not optimum. When possible, line up your cuts along the corners of the hex pattern to minimize burrs. Remember, you have about a half inch overlap to mess with. Test fit the mesh.
Next, mark the holes for the tabs:
This just needs to approximate the size of the tab so the tab will fit through. I used wire cutters to make the cut-outs. You will get some weird shapes because of the hex pattern. Do a final test fit.
Prep for paint:
Wash the mesh material with dish soap and let thoroughly dry. Even if you want it to be aluminum color, I would recommend putting a clear coat over it. I used 2 coats of primer and 2 coats of gloss black applied about 10-15 min apart. Let thoroughly dry.
I am not completely happy with the method of attachment, but it works. And I couldnt think of anything better. (Edit: its been attached like this for over a year now and several DE events. No loosnes or rattles.) I used a small jewelers screwdriver, heated by a torch to melt a hole in the tabs. You just need something about 3/32 or a little larger than the wire you are using. Its easy to drill the lower tabs, but there are clearance issues with the top row. From there I placed the mesh in position and threaded some picture hanging wire across the top row and bottom row of tabs to secure it in place. This pic shows the wire threaded through tabs to secure the mesh
Done. Admire your handy work.
(2020 Update: Please note that several photos for this article appear to be missing, even in the Wayback machine. The original article was written by Flybot who can be found on P-9 Here: https://www.planet-9.com/members/flybot.21548/ perhaps he has the original photos and can send them or update this article.)