Mouse Hover over a part?

How can I make a part have the light blue outline around the the part as if it was being observed by the players mouse?

You can use player:GetMouse().Target in a local script to get the part the player is pointing to. To put a box around it, you can use a SelectionBox. You can create it with Instance.new("SelectionBox"), then set its Parent to the mouse's target.

For more info, visit these links:

http://wiki.roblox.com/index.php?title=API:Class/Mouse/Target http://wiki.roblox.com/index.php?title=API:Class/SelectionBox