How to create mesh density contour

In your case what dimension would you plot? maximum? Average?

In HM, there is a "similar" plot if you go to check elems panel, check for maximu length and use 'assign plot'.

Not exactly what you're looking for, but it might help.

@Qiang Liu what type of element? shell ? solid?

When you speak about "element size" how can you calculate the "size"?

Here're some examples:

For Longest side

For Shortest side

For element area

Have a look at my H3D files in attachment.