My colleague Gabriella Pinter presented a neat 2D rigidity activity at JMM this January that I might write about later, but it reminded me of a 3D rigidity exploration that I've enjoyed running over the years.
This problem was sparked by a question asked by a student in the JRMF Community Math Circle featuring Colored Loops, an activity based on Gord Hamilton's Stirring Paint. While it can be used an an extension to Colored Loops, I'll present it as a stand-alone activity.