I am interested in defining some customized math symbols out of existing ones. For example I would like to distinguish between different types of sums, so beside the usual symbol
I would like to have something of the form
so there are some circles in the corners. It should work just like the usual
\sum command and look exactly like it (except the modification).
How could I create such a symbol in the most painless way? Is
Metafont the answer? Is it possible to modify existing symbols in
Metafont without too much work and expertise?