My video camera doesn't have the same characteristics as my eyeballs, but here's Ghosty from a camera's perspective.

I did a little "thumbnail" analysis to see how practical (or not) it would be to produce Ghosty. For the prototype, major bits included Ping ($30.), Arduino ($25.) a 9 volt wall wart ($7.) and 100 grams of PLA filament ($2.50)--plus minor bits for a total of $64.50, not counting labor. Ouch!

A little searching on the internet showed that the ATTINY85 (I think I can replace the Arduino with this) can be had for $0.90 at digikey. The HC-SR04 (Ping replacement) can be found for $1.19. A 5 volt wall wart can be had for $2.12. The plastic should be $0.50 or less if made by a method other than 3d printing. This gets us to less than $5.00 for most material. So . . . maybe there is some potential for the project.