1. Iteration: 7 Circles
2. Variables: A Parametric Triangle
3. Transformations + Functions: Critter
4. Nested Iteration With Functions: Repeated Motif
(VHS tapes: very subtle, but the tape on each one is randomly sized for length of film and whether it was rewinded/stopped in the middle of viewing.)
(And, alternatively):
5. Nested Iteration + Randomness Gradient: Recoding Schotter