HEPA filter for 120mm fan

This is my take on a HEPA filter that's printable on smaller printers, like the Finder (140mm limit). The filters used are the Kenmore 86889 - which are a pain to get in Europe, by the way.

My advice is to split the hepabox in two parts, right through the middle and print twice. Each print takes about 4.5 hours. Doing so requires no struts, and allows it to be printed on printers with a smaller work area.

Printing in two parts also allows for easy insertion and coupling of the two parts