I am trying to think of some way to position a model to the right side of a GUI. I want to make a shop that has a preview of the item, 3D / Rotating and what not. I also want it not to jerk the camera around changing the position when opened, I would preferable like it keep the camera's current position and just lock the camera where it is. I just cant think of a way to position a part/model into that specific spot dynamically for any player that opens it.
Any ideas/help would be awesome!

2 comments
You could flip your idea around and Place the GUI on the right side of the shop with http://wiki.roblox.com/index.php?title=API:Class/Camera/WorldToScreenPoint. Other than that just use LocalParts so only the player viewing the shop can see their Model. You can then place the camPos and model at any default location.
Your suggestion actually helped me find a way to do what I wanted. In the Camera there is a function called ScreenPointToRay, and with this I can make a ray start from the camera and go out a certain distance. I can then place a part at the end of that Ray. So essentially, I can choose an X and Y offset and place the part there! Thanks for the help!