I made an earthing mat myself, using a stainless steel plate, connecting it through a wire to a 3-pin plug (UK) that only had the earth pin on it. I took out the red and black pins and taped up the hole. I put the socket into the earth plug. This mat is at my workplace under the table.
I found that I needed to place my feet there for at least 30 min to feel better. Although that was the initial month. After that, I don't get the tingles as often.
I'm planning to make an earthing sheet and see if that will work better.
The other earthing I do is weekly feet or body soaking in the ocean. Found out that it removed all my muscle soreness from exercising hard. I get muscle tightness and lose my flexibility for a few days after hard exercise. However I don't get any pain at all. I soak my feet in the ocean 30-60 min. If time permits, I soak whole body. Found out by accident about 6 months ago. This weekly soaking will only work for about a week before I have to do it again. I exercise in gym classes and workouts for about average 8 hrs a week. Calories burnt during that period ranges 5000-8000 calories, depending if I went hiking or not (using heart rate monitor to track).