when my neice was in the service, the family sent stuff out most everyday. one thing I did was to write a letter then cut it up like a puzzle.
wrote a letter on adding machine paper that made a long long long letter.
another letter was started in the center of the paper and written going around and around and around every one was so envious of her unique mail.
once. each fAamily wrote a letter stopped in the middle and sent it to the next family member to continue.
we also cut up photos of family as puzzles too.
include some confettii in the envelope for fun.
She was on a ship and recieved a letter written on toilet paper. the ship was rationing tp for 24 hours. but she felt she was prepared.
Just a few suggestions for a cheery greeting