I have carpet also, and found that a dollar-store silicone trivet works best. Second best is two cheapo dollar-store mouse pads, glued back-to-back, so the grippy sides are out.
I purchased a Steady Betty foot pedal rest and it is absolutely worthless. My foot pedal scoots across it like it's buttered. So, I put it on top of my ironing tray and press small blocks on it. It works great for THAT purpose!