Just provide your own dimensions, mesh kind and cell sizes, height and so on. This thing should handle any fan size and fan guard requirements. I needed it because I broke twice the fragile fins of a 30 mm fan while it was on by waving a screwdriver around. Now it is safe.
Hey, you can even generate filters and bee's nests with it!
Nb: the last pic shows a blue Nylon version made by yzorg, where the raft itself is explicitly left in place for a finer filtering mesh (check the "make" section).

Some settings are a bit weird, especially the mesh_density_ratio, but it is useful to tune the mesh string size, so that your own printer and slicer do a good job. Else you may run in cases where your mesh cell walls are too thin for the nozzle at some places, which may generate messy printing paths.

It think takes ages for the customizer to generate hex meshes with a 100mm+ fan, be patient or chose another mesh kind!

My prints are quite dirty, because I used a raft with Nylon and no retraction (well, this really is trimming line: http://www.tridimake.com/2013/04/3D-printing-with-cheap-trimmer-line.html). I think it is still a good material, but a bit annoying to clean up sometimes!