Vyatcheslav Yatskovsky wrote:

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I usually tackle this sort of thing by first drawing the entire image in metapost code alone. Then, when that works, write a tex command that fills in bits and pieces of the metapost image.

I understand your idea. Indeed, MP code draws underlying grid. How to overlay circles on it using TeX? Please, an example.

First, create a metapost macro to draw a dot on a bar using two arguments. Let's assume this is "mark(a,b)". I won't write that metapost macro for you, you have to do that yourself. \startuseMPgraphic{chordgrid}{e,B,G,D,A,E} drawoptions(withpen pencircle scaled 0.4pt withcolor black) ; draw hlingrid(0, 5, 1, 0.8cm, 1cm) ; draw vlingrid(0, 4, 1, 1cm, 0.8cm) ; draw mark(1,\MPvar{e}); draw mark(2,\MPvar{B}); draw mark(3,\MPvar{G}); draw mark(4,\MPvar{D}); draw mark(5,\MPvar{A}); draw mark(6,\MPvar{E}); \stopuseMPgraphic \define[6]\Ch {\dontleavehmode \useMPgraphic{chordgrid}{e={#1},B={#2},G={#3},D={#4},A={#5},E={#6}}}% \hskip2mm} Best wishes, Taco