Feedback loops can be very cheap and can be modified easily by things to produce some interesting photos.
I used the attached setup to capture these images over 12 years ago and they are accurate to what you actually see on the screen within the maxed out limits of the hardware/software combination used at the time.
To make this interesting, especially as this is a physics forum, I will set forward a couple of questions below with regards to what I had to do to capture the images that I will be posting. I will post the first images and answer the question to show what I did to give you the general idea.
I invite anybody else to answer the questions or post their own feedback loop pictures and pose their own questions with regards to what you did to get the image. Note: none of these images have been modified in any way shape or form apart from the original reduction in size so please don't post modified images.
Only the names have been changed to protect the innocent
(1) How did I create 2-PerfectOrb?
(2) What caused 3-Startled to become startled?
(3) (a) What happened straight after 4-DamnedSpot was captured?
(b) What happened if you did not capture 4-DamnedSpot
(4) What is the only thing altered between 5-Blue and 6-Orange?
(5) What is different between 7-Fractal, 8-Flare and all the other pictures so far?
(1) I gradually skewed 1-1-Winiverse until I had 1-2-FernShell. 2-PerfectOrb was not far away.