Built to Scale (組み立て,Assembly?) is the first game in Rhythm Heaven. It features recurring Widgets that you must shoot rods through. Getting a perfect unlocks the Built to Scale soundtrack. The sequel, Built to Scale 2, is unlocked later on.
The player shoots a rod through the center of the squares that pass by each other. To rhythmically succeed in this game, the player must follow the pattern "do-re-mi-fa-sol" with the music, flicking on "sol". During the level, the screen becomes dark with a spot light in the middle and it becomes harder to rely on visuals. This part of the level forces the user to use the audio to win.
Flick: Shoot Rod
Hit: The rod hits both squares and connects them with a satisfying clink sound.
Barely: The rod will hit both squares, but knock them down, only sending the rod itself down the conveyor belt (Barely counts as a miss).
Miss: The rod and squares never make contact, and the squares will roll into the nearby slots and disappear through them.