Crossover positions flanked by tsDNA feature double crossovers. i, Periodic repetition of 20 bt TFO target domains (240° helical rotation) secures up to three neighbors per helix and folds the scaffold into a honeycomb lattice. j, Periodic repetition of 15 bt TFO target domains (90° helical rotation) secures up to four neighbors per helix and folds the scaffold into a square lattice.