There is a [url=]pulley simulation[/url] which include 2 and 3 pulley. But the size of the pulley is fixed.
The above simulation did not consider the mass of the pulley.

You are welcomed to check out [url=]Atwood machine with massive pulley[/url]

Please write down in detail what are you going to do with the simulation. May be we can create one for your case.