I saw this Biostar post on Venn diagrams for GO term overlap. And this tool could be modified to do something like I wish, but was wondering if there's a tool that can make nicely proportional Venn diagrams by entering just the number of elements in each set and intersection. For instance circle A has 10 items, B has 10 items, A+B has 6 items. Drawing them proportionally would be nice, but not essential. Also nice, but not critical, would be something open source which could be integrated with a suite of Perl scripts.
P.S. not using any standard GO terms, gene IDs, etc. This is for CNVs. So elements would take the form of chr1:100000-200000.