So you don't really want a hash, but rather a string. You might try something based on this Perl debugger session:

  DB<1> @a1 = (red,blue,green);

  DB<2> @a2 = (black,orange,white);

  DB<3> print  join ',', map {"$a1[$_]:$a2[$_]"} 0..2;
red:black,blue:orange,green:white
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