get a couple of SS frying pan splatter guards, pull handles off both and pry the rim off one. (£shop??)
then use a length if split beerline to clamp the two together to create a mesh envelope/garth style mesh filter..
into the edge of one mesh, fit a rubber grommet suitable to fit snugly around your dip tube to push fit it into the filter..
edit be mindful of needle sharp wire ends of the mesh you pull the rim off