Exploding a random string

How would one "explode" a random string? What I'm after is; taking a random string of n length

characters=$(</dev/urandom tr -dc '1234567890{}[]`~\/><!@#$%^&*()_+=-abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ' | head -c${n})

exploding the characters such that they fit within k space

k=27

a r a n d 0 M B u n c H 0 f

where k is the "exploded" legnth.

Ultimately I would like to set a carrot "^" under each of the characters and have it follow along what is typed.

see my other post here