I’d tried ceramic, wood, laser printed, popsicle sticks, etc. On tile or wood flooring, raising my cables mainly keep dust bunnies from clinging and very little else. On carpeted floor, I do hear a difference especially during dry winters. I found them most effective with non-shielded cables, speaker and interconnect cables alike. If one takes the extra effort to use cable risers, he/she will mostly make the extra effort to dress their cables properly. Such as separating power, interconnects, and speaker cables from each other. Usually an inch or so will do. Should cables touch,try one’s best to cross signal and power cables at reasonable angle. More perpendicular the better. I humbly believe cable dressing pays the biggest dividend.
Finally, I came across and currently using a few Rebar Chairs in parts of my cable web. Cheap and effective. Many styles and heights to choose. One with perfect slot to slip in my Analysis Plus speaker cable yet able to hold a two inch diameter power cable with slight modification.
Hope you find this useful.