My best guess is that it's a device for creating title slide animations back in the days before this became more routinely done via Corel Draw on the PC. Typically the process started with taking a macro copy photograph of a pasted down bit of clean black and white text, printed out on a dedicated text printer (these pre-dated laser printers). Then, imagine taking series of copy slides of this plain text, in this case each with a slightly different rotation, often on Kodalith film as a reverse mask in double exposure over a photograph, perhaps solarized or posterized, with god-only-know what other mind-blowing special effects. The final use was often to take all these slides and merge them with dissolves in a six-projector slide show, in an animation. Spinning or spiralling text. Helped keep your audience from falling asleep. Think PowerPoint, but mid to late 80's (before even Windows 1.0).
Looks like something out of the Wess Plastics catalog circa 1988, actually. There were all kinds of these for AV title slide making, ones specifically for neon glows, others with little doors for making masks/ slices, etc. And you can bet your bottom dollar that this sort of pro AV stuff was not cheap, back in the day.
Reminiscing about this sort of stuff I'm often struck in a similar way to the astonishment I feel to step back to realize that our forbears built so much of the infrastructure we take for granted (e.g. the Brooklyn Bridge) with coal-fired steam power, and before even that, water and mule power.
