> ceramic fillers Thanks for this tip. I'm planning on buying a friend a tumbler for xmas, and if this works as advertised, I feel this would be a must have as

> ceramic fillers Thanks for this tip. I'm planning on buying a friend a tumbler for xmas, and if this works as advertised, I feel this would be a must have as part of the gift. Edit: of course, TFA mentions this as well for those willing to click the link <facepalm>