This is a filter cage that fits the 50mm x 50mm x 15mm horizontal flow fan that the Prusa i3 MkII has. I was tired of having to clean the fan blades as often as I did (I have cats - and a dusty house apparently) so I designed this cage so I could wrap some filter material around it and catch the big stuff.
After using it a month, I must say that it works well. It stops the cat hair and larger bits, but the talc type dust still goes through (this is not surprising since I am using pretty coarse 3/16" thick filter material from Amazon )but it catches a lot. There is enough foam in that sheet to make, oh like 50 foam rings for this. It'll last forever - if you don't lose it. I used some CA glue that I had laying around to fuse the ends of the foam strip together.
Anyway, I wanted to make it without using supports, and since I have a soldering iron I can dial down to 210C, I just made the two halves so that I could melt the ends of the rods to hold the two pieces together.
The holes are intentionally undersized so that I could use an X-Acto blade to carve out a little at a time so they would be press fit over the SHCS so I could just press it on and pull it off without tools. It has never come off unintentionally.
I left it hairy and dusty in the photos so you could see how well it works. That is after two weeks of printing ~8-10 hours a day.