I use a replacement s/s mesh screen - the type that are used on those camping toasters (about 170mm x 150mm). Fold it round on itself to form a tube, fold up one end and shove it over the spiggot inside the boiler using a cable tie to hold it on.
They only cost a couple of bucks at the supermarket and if it goes in the weekly shopping its free
They only cost a couple of bucks at the supermarket and if it goes in the weekly shopping its free