How hard could it be to make a collapsible silicone container? Turns out, it’s really, really hard — collapsible containers have rigid guidelines. Just ask [Eric Strebel], who failed dozens of times ...

Measuring the “hardness” of soft, spongy elastomers—foams—is an inexact science. There is usually a surprisingly broad spread in the data normally provided by devices such as a durometer, a tool for ...