D4 Trapezium Design Notebook: each design is a flurry of ideas and concepts merging into one--I try to keep track of the process with notebooks specific to each design. The D4 Trapezium was second D4 design after the full size ledge was produced funded by the successful Kickstarter. This design fits in a daypack and has been used extensively in the Tarkine Rainforest in extreme conditions. See below for more tips on build.