My long suffering husband had a birthday last month and because his time in the military was spent in the Navy, I decided to make a nautical themed card for him this year. I found this card, which had a link to the flags, so I printed them out and went to work.
It says Happy Birthday in nautical signal flags! I just drew the lines with a black marker and used foam adhesive to pop up the flags along the lines. The sentiment and stars are by Hero Arts. He liked it :-)