With the Kärcher SE 4002 spray extraction cleaner (what a product name!) I prefer using the paper filter (part number 6.414-552.0, 122 x 114 mm cartridge), when vacuuming dry matter. These filters last long, except that the rubber ring around the vacuum inlet quickly starts cracking, after which it is unusable. Except, of course, if you print this part Kärcher likely would like to ban, as they won't be selling much filters to me or others using this. Print in NinjaFlex etc rubbery material, place on top of a filter and push the filter into the vacuum like always.
According to Kärcher, this filter is compatible with SE 4001, SE4002, WD 2, WD 3 and variants.https://www.kaercher.com/int/accessory/cartridge-filter-64145520.html