The string model is about qualities of movement through the garden and the events that shape the movement. The foam model is about the qualities of space in the garden (and how they connect) along with the events that shape the movement.
Read the article: Tschumi_Sequences.pdf linked to the left.
Do a Foam model using foam (duh), wire, rubberbands, glue, chipboard, and other connectors that can make a systemic way of specifying space and event in the garden.
The wire cutters are set up in 125 and 130 of Solberg.