I have been thinking in terms of a very low coefficient of expansion solid made from powders of ground glass or mixed materials like a mix of sugar, kaolin, and sand, or many similar possibilities. If the powder is fused the part not fused can be washed away by water leaving a fine lattice of fused material. If the lattice is silicon carbide (sugar & sand) it could make a great high temp heating element capable of temps in excess of 2k degrees F. The first question, of course, is the ability to experiment without injuring the Glowforge and the second if a preformulated “card” could be included in the list of available materials.
Has anyone tried anything like this? Raku clays might also be a consideration.