Look at your original payment. You should see the seller's email address there.
Then go to Paypal's Send Money and .. send money to the email. You might want to note the item number,especially if the seller is busy, just to help him keep his books straight.
This will not cost you any fees.
If you have not left feedback, now is the time. You can also leave Detailed Seller Ratings. Time in transit is not "Handling time" that refers to how long it took the seller to get the item in the mail, btw.
If you have left feedback, you can add a RESPONSE saying that the item did arrive and that you repaid the refund.