Reverse Engineered Object:Selection

I'm to choose an object as a start to our reverse engineered object project.

Requirements:

Made up of parts

Fits in the jaws of a caliper

Original choice

Stationery is designed simply for function with thought for mass production. Usually constructed from a handful of parts and easily disassembled. Throughout my life in school I have collected an assortment of stationery, I went through it looking for one piece with smart design and clean looks. 

Choices:

I posted a bit late so I have seen a few student posts so far. Bulldog Clips have been chosen. The Compass Ruler is a nice choice as a functional model in most mediums. Unfortunately I can't seem to disassemble mine. The Cork Back Ruler is functional in most mediums as well but the form is very basic and the two parts (cork and metal) are not meant to be disassembled. I'm keen on the pencil sharpener. It's body works in any medium. Two screws are included so there is potential for me to push myself. Modelling the blades will be a lot of fun, I like the idea of 3-D printed plastic blades. Nonfunctional of course but I could substitute the metal blades if I ever need to use the thing.

Thanks,

-Caleb