P.B.
K., My son was in the Navy for 10 years and deployed 4 times. One of his favorite boxes that he received was his "Birthday Party in a Box" and "Christmas in a Box". For the Birthday Party box I sent homemade cookies, decorated with sprinkles, candles, balloons, a can of punch, plastic tablecloth, party plates, goody bags which can contain small toothpaste, deodorant, etc - anything that he associates with a birthday. I always sent Fruity Pebbles because that is the only cereal he asked for when he was away. Then I took pictures of family and friends and taped or stapled them to the inside of the flaps of the box so that when he opened the box, he could see them "around" his boxed party. I even filled a balloon or 2 to use as filler. He said he really felt loved and special on his birthday because of that box.
On Christmas, I sent a small Christmas tree with all the ornaments to decorate it. Send anything that is special to your family and to him about Christmas. I also sent one of those motion sensor things that sings "Merry Christmas" when you get close. He said the other guys really enjoyed that box as well.
As far as the party, have the people you invite write him a letter about how they feel about him. Put those in an album and send them to him in a care package later on. I put ours in a scrapbook album, along with pictures of the family or friend who wrote the letter. He has that album still . It can even be a small one or several small ones, something he can tuck away for private moments when he is lonely or homesick.
Thank you for raising a son willing to serve our country and thank him for me for being willing to serve. God bless!