I have the static grass applicator from Noch. I found it for a special price, but still a big piece of a hobby budget for a retiree on a fixed income.
I have use it to apply W/S and Siliflor static grass and am delighted with the results.
It does take some practice and to that end, I elected to take a scrap piece of extruded polystyrene (= pink foam) and paint it and then experiment with various application steps, i.e. such as applying different length and colors in a layered manner.
I also experimented with using diluted white glue over existing ground cover.
I find most satisfying results by doing small areas and applying several lengths and colors. I also have intemittently used the grass or weed clumps.