A maker called Crafterboi built a 3D-printed, fan-assisted spacer frame that mounts between your back and your backpack, eliminating sweat buildup during hot weather. Two 5V fans at the top actively push air through the gap. The frame is printed in PETG, not PLA, because surface temperatures on a hot day can exceed PLA's softening point.
The design logic is straightforward: an open lattice creates airflow that passive spacing alone cannot guarantee, and the fans force that circulation even when you are stationary. What makes the build process worth reading is the prototype stage. Crafterboi first validated the concept using a pizza box before committing a single gram of filament.
This is not the first cooling backpack on record. Earlier attempts used Peltier modules and evaporative coolers, but link rot has erased those original project pages. Crafterboi's version is the most accessible iteration to date: consumer fans, one common filament material, and a geometry you can iterate cheaply. The Instructables writeup includes the full print and assembly details.
[READ ORIGINAL →]