Perl 6, 29 bytes

{[~] keys (' '..'~')∖.comb} 

Note that the result is random because Sets are unordered.

Test it

Expanded:

{ [~] # reduce using string concatenation # (shorter than ｢join '',｣) keys # get the keys from the Set object resulting from the following (' '..'~') # Range of printable characters ∖ # Set minus (this is not \ ) .comb # split the input into individual characters } 

There is also an ASCII version of ∖ (-), but it would require a space before it so that it isn't parsed as a subroutine call.