Using lessons learned from the Airship Regatta competition, the idefx prototype is being rebuilt. One change will be to separate the envelope into an interior and exterior envelope instead of using a single envelope for both gas retention and resilience. The goal is to improve gas retention, in order to reduce operational costs. The new inner envelope is constructed using 12 micron (0.5 mil) aluminized Mylar, glued together using the "accordion" method. The material weighs 16 grams per square meter. The envelope is 2.54 meters long and 0.6 meters in diameter. The envelope has gone through 2 passes of leak detection and mitigation, and so far seems pretty solid in terms of gas retention.