There are quite a few ways to map aspects of points outside the set to colours or other variables. It’s been a long time since I looked at Frax but I seem to re

There are quite a few ways to map aspects of points outside the set to colours or other variables. It’s been a long time since I looked at Frax but I seem to remember it maps iterations, the direction in which points are escaping, and a few other things to a height, colour index, speculative index, etc., and then renders the set by rendering that surface. It’s not as fun as the four dimensional construct that is all the Julia sets, but probably easier to explain to people.