My experience below, hopefully it's helpful to someone.
1. Received certified letters from C&C Honolulu after ~150 days. Since signature was required and no one to receive, a trip to the post office was necessary.
2. Received 1 letter for each handgun qualified on (e.g., 2 handguns = 2 letters = $20).
3. Went to the Registration Room at HPD.
4. Provided letters, ID, cash and immediately took a seat outside the room.
5. ~30 minutes later, name was called and letters, ID, LTCs, and cash receipt were returned.
6. LTC observations:
a. Received 1 plastic LTC for each handgun.
b. LTC expiration date is 1-year from the pickup date at HPD.
c. Included on LTC are photo, height, hair, weight, eyes but it states, "This card is not to be used as a valid government issued photo identification card".