in this question a composite symbol "diamond plus" is requested for use with plain TeX.
a good-looking version was provided, but it works in only one size.
if the same symbol is needed for a title or a footnote (i.e., in a larger
or smaller size), the image produced by the provided code will be deformed.
this would be true for LaTeX as well as plain TeX, and is a different
problem than the one addressed by
the overlay technique is sensitive to a couple of things:
the need to use explicit dimensions, and (often) the need to pack at least
one of the components in a box, which "freezes" the size at the current value.
\[math]clap, while very useful, are underlain by boxes, so
are subject to the "single size" limitation.)
there are some TeXniques than can be brought to bear on this situation:
to adjust for relative current size, the
dimensions can be expressed as
muto accommodate to the current size, but they must be employed carefully at appropriate places in a definition to get the desired effect. it is also the case that (for computer modern fonts) the different design sizes may not have the same aspect ratio; this is particularly true for bold vs. normal weight.
another possibility is to take advantage of the fact that
\mathopwill vertically center a single glyph on the math axis.
has anyone come up with a robust, flexible mechanism for overlaying glyphs to form a composite symbol that will reliably adjust to the size of type in the current environment? for simplicity in a first cut, it's acceptable to stick to computer modern/latin modern fonts.