I was commissioned to build this large arm-mounted grapple launcher from the 1989 Batman. This is the device that shoots two lines out and allows Bats and Vicki Vale to escape the art museum scene, and causes Jack to mutter the famous "Where does he get those wonderful toys?".
The prop isn't seen onscreen very clearly so I found a number of pre-production photos that showed most of what I needed to know. My customer also wanted it to "work" ... at least have the two shooters snap from front to side position like the do in the film.
I modeled the gauntlet in Fusion 360. The final piece was a combination of 3D printed pieces and real metal frame and tubing. A trigger mechanism inside allows you to trigger the two shooters with the flip of a finger.