The Tau Cannon, a science fiction energy weapon from Half-Life computer game franchise, has captured imaginations of gamers and 3D artists for over 20 years, with many drawings and 3D renders published in online communities.

I always wanted one, so I decided to build my own to get more experience with sheet metal and CNC fabrication, rubber casting, and tube bending.

I started with sourcing external components because it’s easier to reverse-engineer a sci-fi prop with no known dimensions by finding real-world equivalents of a few parts and sizing everything else relative to those.

The top and side handles provided for good reference points in ensuring the size of the finished prop will fit a person.

Installing picatinny rails added another dimension of realism — you can mount tactical straps, laser sights, flashlights, and even bipods on those.

Body and stock were machined out of aluminum, the coil and battery covers made out of sheet metal, and toroidal transformer cores were 3D printed.

I also designed some rubber parts: a recoil pad, finger grip near the trigger, and a hose panel-mount connector. I still need to find a fitting wire gauge for winding the toroidal cores, weld, and paint all the parts.

Finally, I added an on-board computer (a Raspberry Pi 4B) that processes video from a small webcam mounted near the muzzle and uses the OpenCV HOG Descriptor to detect people in real-time and draw cross-hairs over them.

Clone the GitHub repository to download CAD models and printable STLs.