I recently received an email from a gentleman who described to me a scale he had made from a popsicle stick and a toothpick for a fulcrum (pivot point) that could differentiate 1982 copper and zinc pennies.   For those of you who don’t know, they made both Copper and Zinc pennies in 1982.  The best way to tell them apart is by weight.   The copper pennies weigh 3.11 grams versus 2.5 grams for the zinc pennies.

After reading the email about the popsicle stick scale, I decided to try to design one and 3D print it, and this is what I came up with:

3d scale1

And when printed, it looks like this:


For more info on how it works, watch this youtube video:

Here is a link to download the schematic files if you want to print one of these yourself:

STL file:  http://www.junksilverbook.com/penny_v5.stl

FreeCAD FCSTD file:  http://www.junksilverbook.com/penny_scale5.fcstd