New
#41
I've now got the parts for the filter. They are a cut-to-fit vacuum cleaner filter (should be able to get 2 filters from that), a metal wall vent (with slider, which I shall remove to make room in the recess for the filter material), and some nuts/bolts to fasten it to the side panel of the case (on the inside). Just need to drill the holes for the bolts.
I was considering magnetic strips to hold the filter to the side panel, but couldn't locate any. I also thought of a wire mesh, which I would fasten by weaving picture wire through it and the outermost holes in the grids in the side panel. I rejected this idea on the grounds that it would be fiddly to install, and would not lend itself to the easy cleaning/replacement of the filter as needed (in addition, it would, in all likelihood, squash the filter material thereby reducing its effectiveness).
My solution, therefore, solves these problems. It allows the filter material to breathe, and it also makes for easy maintenance.