Press 'r' for randomness.
Press 'h' to toggle interface.

View on a bigger screen for more control.

Scale 2

Scale each cell by a random value.

Logic: Similarly to Scale 1, each cell is scaled down by a random value from a set of 20% to 100% (with 20% increments so five values in total), but proportionally along both axes. Depending on the Scale Corner choice cells are scaled from that corner.