If you have a Francis Francis espresso machine that makes espresso with an Illy iperespresso capsule, you are restricted because only Illy makes them. What I found was that the capsules make really excellent espresso, but I still had half a can of espresso coffee (Illy, by the way) that I wanted to use up in my new machine.
I was also intrigued by the capsule and wondered if I could open it and reuse it.
The capsule is in three parts, as you can see from the image. The bottom end goes in first to the machine, the body holds the coffee and the top holds everything in. The color tells you what kind of coffee--black for bold, blue for long (for "long pulls") and green for decaf.
The bottom is just a snap on cap while the top is bonded to the body--there's the rub in opening it.
Step 1: top removal
Here's a capsule with the top removed. I found two ways to do it. The first (as shown here) was with a bandsaw. That was messy, but I still had a fairly good result as you can see by the picture.
The second method was with a razor knife. That actually gave a better result, but is also a bit more hazardous. Careful and slow cutting of the top, just shaving the lip where it bonds to the body is the key.
Once the top edge is removed it is easy to pull the top out of the recess that it sits in within the body.