Since I just have two projects where I need grass flock, I looked at the prices on the Internet. These are ok, even if sometimes through middlemen a little more expensive than normal. I then still prefer to look for a video tutorial alternative and found the video How to make Flock in 15 Minutes from Miscast. I have copied this tutorial here. I will make a slightly larger quantity than I am willing to buy.
Since I wanted to test only a small amount, I used sawdust that I had left over from another project. I put them in a wide bowl so that I can mix the flock better. I find cups too small for this. Then I added a small amount (ca. 1 tablespoon) of acrylic paint to the sawdust. In the next step then add nail polish remover and stir everything well with an old toothbrush.
This worked super well the first time and I was massively surprised by the result. The flock has the same quality as from an online store for a tenth of the price. You can also experiment with different colors, as Miscast did in the video. Since I had time I was able to take the flock to the drying cellar and let it dry there. Then just sift it and sort it into individual trays that I can use for different projects.
In the future I want to produce flock with other materials, because I think that we throw away too much garbage and I can not only save money, but also protect the environment.
 In the last few weeks I've noticed how many good modeling and artist supplies products come from England. Unfortunately, the Brexit has made them really hard to come by and I have to keep looking for alternatives that don't cost me my entire fortune.
 As I could see in the video, Miscast uses oil paints, but I can't afford them at the moment. I have therefore used the old acrylic paints, which also worked very well.
 The nail polish remover must contain acetone, because otherwise the color will not be diluted properly and the alcohol will ensure better evaporation.