It is an old movie trope: a robot grips something and accidentally crushes it with its super robot strength. A little feedback goes a long way, of course, but futuristic robots may also want to employ soft grippers. [Jessica] shows how to build soft grippers made of several cast fingers. The fingers are cast from Ecoflex 00-50, and use air pressure.
A 3D-printed mold is used to cast the Ecoflex fingers, which are only workable for 18 minutes after mixing, so it’s necessary to work fast and have everything ready before you start.
Once cast the Ecoflex is fairly easy to puncture, a paper clip can be enough to punch an air hole through the wall. There may be some leaks that are easier to detect if the part is submerged in water, in which case any holes can be patched with fresh Ecoflex. If an air channel is clogged it may be necessary to recast the whole part, but the mold is reusable.
Speaking of reusing the mold, it’s also possible to create three more fingers and use a 3D printed hub to make an entire gripper hand. As a practical matter, you should probably have force control. Soft grippers can be very — pardon the pun — flexible.