My partner in the Mail Art Swap received, so I'm going to go ahead and post this.
I made the envelope out of heavy 12" by 12" paper with the pattern on the inside. Here is the front:
The background is acrylic paint, and the tree is made from hearts punched out of magazine pages. I had originally planned to do the whole thing in hearts, but it took a lot longer than I expected to assemble the tree, so I had to change my design or I wouldn't have been able to send it out on time. I really like the effect though:
Here is the back:
My swap partner likes koi fish, so I looked up some of the specialty breeds and did paintings of them in acrylic paint. I wrote the Japanese names with silver Sharpie for a little sparkle.
The center on the back is just a weight I put on it to keep the top flap from popping up when I took the picture, but now I'm kind of sorry I didnt' make a seal to put in the center, as I like the origami paper with the fish. (hmmm, I'm getting an idea for a mixed media piece . . . )