Gift 2: A quadropter or DIY drone kit
Quadropters and do it yourself (DIY) drone kits could be a popular gift that keeps your engineer happy for many moons (but not necessarily out of trouble).
End result of DIY Drone Kit. Yes, that is a bicycle wheel. (Source: Instructables.com)
Community-submitted drone image from DIYDrones.com. (Source: DIYDrones.com)
Skybotix CoaX Autonomous UAV Micro Helicopter Drone. (Source: Robotshop.com.)