There are multiple Spare Parts hidden across every Level. With Spare Parts, and a little innovation, you can create anything from more Lives to a few extra Boosters!
Most Levels will have more than one Spare Part to collect. The Spare Parts that can be collected in each Level will be highlighted under 'Chance to Find' just above the 'Play' button. Once collected, Spare Parts can be used to craft Boosters, Lives and Gold by selecting the bulb icon on the top left-hand side of the map screen.