Someday I should swap using the cap from my Space Pen with for a Colibri 7mm cigar punch with retractable blade (and pen clip). Satin chrome & polished chrome finish (shown), available in a variety of finishes.
There are three basic types of cigar punches, a bullet punch, Havana punch, and multi-punch. but this bullet punch is the popular bullet shape that fits on a keychain (or pocket as shown). The punch is twisted to expose a circular blade, used to cut a hole in the cigar cap. This cut is preferred by some, as it exposes less of the filler and binder and reduces the chance of tobacco ending up in the mouth.
Shop Colibri: $40