I always seem to lose the caps to my USB thumb drives. I figured I could use some Sugru to make a new cap.
I didn't want to risk gumming up a USB drive, so I decided to use a USB cable for the mold.
Step 1: Make Sure the Cap Will Release the Sugru
I didn't want to put a releasing agent on the USB cable unless I had to, but I also didn't want the Sugru to bond to the USB cable. I decided to cut a small part of the Sugru wrapper to use around the USB cable.
In the photo, the wrapper looks pretty loose, but I was able to get it tightly wrapped around the end of the cable and secured with a small piece of tape.
Step 2: Sugru It!
I molded the Sugru all around the end of the USB cable until I was happy with the shape. When I was done, I trimmed off a bit of Sugru near the open end of the cap.
Step 3: Let the Sugru Setup
I let the Sugru setup for about an hour before pulling it off the cable. It released with no problem.