I've seen a number of threads/posts on this forum (and many others) looking for a cheap and easy way to make dust filters for PC intake fans. Some suggest buying specific products designed for PC fans (£2-£5 for a 120mm x 120mm filter) Some suggest redneck alternatives such as tights/tumble dryer sheets etc. (all great solutions) However, I've found the perfect solution. I've just purchased two sheets of the real foam (as supplied with many higher end cases such as Lian Li etc) Each sheet is 2m x 1.5m, comes in a few colours and a range of densities and is cut to any thickness you want!! The best part..............each sheet is less than £15. That's £15 to buy enough dust filters to protect over 100 fans! Here is the company - Filters Scroll down the page until you get to Reticulated Foams (open cell foams graded in ppi, Pores per Inch) The standard PPI (pores per inch) supplied for PC dust filters is around 60. I've ordered one sheet of 20ppi (for high air flow) and one sheet of 60ppi for extra protection. Just call them up, ask for a quote, they will send you a pro forma invoice, then you pay with cheque or bank transfer - they then ship (cost around £9 for 2 sheets). I hope this info is useful for some of you avid system builders/modders.