Here is my custom build system for compiling markdown files including plantuml chunks in sublime-text 3 on Linux.
{
"cmd": ["/home/steve/.cabal/bin/pandoc","--filter","/home/steve/.cabal/bin/pandoc-plantuml-filter","--filter","/home/steve/.cabal/bin/pandoc-citeproc", "-s","--toc","--bibliography=/home/steve/bibtexOK.bib","--template=/home/steve/template.tex","-o", "$file_base_name.pdf", "$file"],
"selector": "text.pdf.markdown"
}
Obviously you will have to replace the /home/steve parts with your own path which has to include your pandoc installation path, otherwise pandoc will fail when you call it from Sublime Text. Took me a while to figure that out.
This assumes you have a cabal installation of a plantuml filter.
Plantuml makes it really easy to do nice graphics like this:
Alt text