Rounded corners on BoxGeometry where faces not touching

[hofk]

For evenly rounded corners on all sides, you can use the construction as in

Magic Box Example 19.

See
Addon to create special / extended geometries

GitHub - hofk/THREEg.js: three.js addon to create special or extended geometries. The addon generates indexed or non indexed BufferGeometries.

Simple construction of the corners see from the collection
Beginner example step 12, function eighthSphere( n )