SoftTouch 4" Square Adhesive Anti-Dent Carpet Protectors with 5/8" Spiked Bottom, Self-Stick Spiked Furniture Pads for Tables, Beds, Sofas, Chairs, Set of 2, Clear

I'm sharing here because this thread comes up in a lot of google searches when you search for "standing desk", "flexispot", "carpet", etc. My FlexiSpot desk (E7 Pro with a 55" desktop) is set on top of VERY deep-pile carpet (~3/4in), and one of the weirdest/hackiest upgrades I've cobbled together is what I call "sleds" for the legs. For two 32" sleds, I used two sets of these acrylic shelves (4 total). You could get the set of two 36" shelves, but that was too long for me, and I don't have the tools to cut thick acrylic. I used five pairs of these anti-dent carpet pads (ten total 2x2 grids) along the bottom of the shelves: three 2x2 grids on the back sleds to bear most of the weight (mine is the "semi-C" leg structure), and two 2x2 grids on the front sleds. The trickiest part was getting the desk legs situated inside the sleds -- it was a two-person job, one person to lift one side of the desk, the other person to place the sleds into position under the legs before settling the desk back down. I can now scooch my desk forward and backward by myself when I need to (sitting on the floor and using my legs to push each desk-leg incrementally forward/back). The sleds don't move at all, because of the weight of the desk and the spikes holding them in the carpet. And, while these desks will always 'wobble' at height to some extent, it feels more stable front-to-back when set in the sleds, closer to hard flooring. Theoretically, I think you could place the desk in these sleds with the wheel attachments installed, and because of the 'lips' on the acrylic shelves, the desk could only move forward and backward and wouldn't fall off the sides. But the wheels make the desk too tall for me (I'm very short and use the lowest setting when sitting), so I haven't tried that. (You probably would also need to make sure to get single-piece shelves instead of two 16" sleds per side, since it wouldn't be good for a wheel to sit on top of the 'break' between the two pieces.)