When you say you have Vegas 8, is this Vegas Pro 8? ‘cos if you DO have this Pro version you sure do have the Bezier Masking feature. Within this you can set 4 points for your rectangular mask very accurately indeed. And this is WAY more flexible than Cookie Cutter too.
If you do have VP8 then click on the Pan/Crop Icon, it’s located at the right end of the Event. Once the Pan/Crop Window is revealed, look at the bottom Timeline and check the “MASK” then all the Bezier Mask drawing tools become available to you.
So, the workflow would be:
1] Place solid SONY colour on track 1
2] Place video on track 2
3] Go back to 1] and set up the masking session by accessing the Pan/Crop > Mask procedure.
4] Insert the 4 “Anchors” for each corner of the rectangle and then use the “Normal Edit tool” to accurately position each Anchor by either using the Grid Overlay in the Preview window and/or the actual X and Y positional tool to enter numbers directly or the slider.
Now, having said all the above, once we have created one or two or a series of rectangles we can save them as our own templates and recall them back through the Mask option.
So, do we have a plugin that MAKES masks? Well yes, I’d say so. Plus you get to keep your hard won work and recall it in the future too. Do we have a drawing plugin for VEgas? Not that I know of. But of course you could employ a Graphics package and work that way around? But a direct graphics package that creates “masks” for Vegas? Not that I know of . . ..
HTH
Grazie