Period 2 in a moderately low height. Depending on the shape of the reagents, there is a finite limit to the number of reagents that can be grabbed because arms can only reach the input if they start with a gripper over the input or 1 hex away from the input. Period 2 is possible on polymer puzzles where there are no mandatory consumption glyphs, all atoms required in the output are part of a multi-atom reagent, and the output shape is small enough relative to the finite limit of grabable inputs.