My Mark Rollins Class A Climax needed a spark arrester. The problem was finding some material that looked right for the wire screen. The answer came in the form of a Mr. Coffee permanent coffee filter that was left over from a defunct coffee maker. I’ve looked at some others as well, and some brands seem to be made from a sheet of thin metal with small holes punched in it. The Mr. Coffee (and my current Krups) filter is a finely-woven wire mesh – just right for HO. There is enough material in one such filter for all the spark arrestors one could ever want to make! I started by cutting a strip from the filter material – it is quite easy to cut with scissors and to follow along the mesh for a straight cut – for the cylindrical body of the arrestor. I overlapped the ends slightly and glued with gel ACC, using my tweezers for a clamp. Next came the solid metal bands, made from HO scale 1x4 styrene strip. This arrestor is about 0.5 inch (12mm) outside diameter; for a smaller one, a scale 1x2 might work well. I wrapped the strip around the wire body at the top and bottom of the cylinder and secured it with ACC gel, again using the tweezers for a clamp. The photo shows a piece of the Mr. Coffee filter material and the styrene 1x4 strip as well. To finish the cylinder, I cut four short strips of the styrene 1x4 and placed them vertically at 90 degree intervals. For the top, I traced the outline of the cylinder onto the Mr. Coffee mesh and cut a circle with the scissors. The problem was: how to neatly secure the top to the body? The solution is shown at right. I fitted a strip of the 1x4 styrene inside the cylindrical body, overlapping the ends slightly, and glued it with ACC. Then, I glued the resulting circle on edge to the circular top. When dry, the cap fitted into the body very neatly, as seen below: A coat of Polly S 'Grimy Black' finished the project, and the photo below shows the result.