Applies to 2021.0 Update and later
Let parts drop and settle in the build room using simulated gravity
You can use the packer with the default values and without any parts selected right away, and only make adjustments as and when required.
The packer finishes once all parts have settled and are stationary. Packing can take an undetermined time as new gaps for parts to settle into may only be found after prolonged simulation. You can cancel packing at any time.