Builder’s challenges are used to introduce an element of additional suspense for the audience and the builders themselves. While the dominoes are already toppling, one or multiple builders are tasked with filling a gap that was intentionally left out before. If they succeed, a barrier opens and the chain reaction can continue. If they fail, everything behind the barrier will not topple and thereby not contribute to the overall tally of toppled dominoes for a potential record. Builder’s challenges can come in various creative ways; the picture shown here is just the simplest variant to illustrate the concept.