I have a 'light writing' streaklet set up using Trapcode Particular (ala the old ipod nano ads). It uses a custom shape, colour gradient and size/opacity variations. The streaklet lasts for around 10 seconds. What I would like to do is specifically alter the shape of the streaklet during this time. So for instance, as it is drawn and appears it has the shape of a square, over time I want to have it change its shape to a circle. I can do this easily enough with Stroke, 3DStroke or Vegas as they use mask paths but none of those have the specific look that I want in terms of streaklet shape etc. and Particular uses position keyframes rather than a mask path so the path shape can't be altered in the same way. I'm using Particular 1.5. Is this something that could be achieved using version 2 or is it, as I suspect, not possible?