Since co-workers have regularly seen me working on a project during lunch, the question has come up. I politely refuse, and that has worked. One lady I worked with actually bought a diecast like her husbands car, and she even painted it the same color, so I did make license plates and other stuff for her "build". Hey, she at least put an effort in, and found the end result rewarding. Her husband was thrilled to have a model of his car.