Meta Box Columns is an extension of the Meta Box plugin which can reorganize fields by putting them in the same row aiming to have a better layout, and see/add information easier. It supports to organize fields in a 12-column grid with ease.
When developers register multiple fields in a meta box (such as information about an artist or a person), listing every field one by one down the side might be boring. This makes the edit page too long and hard to see the overview. The Meta Box Columns can help you to make it organized and clear by putting the fields into a 12-columns grid. This shortens a lot the edit form and lets you see all the information immediately without scrolling down.
To improve the UI of the form, please consider using this extension with the Meta Box Tabs extension. It helps you organize custom fields into tabs. Both plugins work nicely together.
Supports 12-columns grid
Easy to adjust old code to add columns to meta boxes
Feasibly integrate with themes