There are many good DIY headboard ideas for a divan bed. Some of the best ones are plank headboard, squared off headboard, framed fabric headboard, and window of opportunity headboard.

I painted my headboard white.

I do not have a headboard for my bed but I plan on purchasing one very soon. I find a bed looks better with a headboard.

A king sized headboard can be converted to work with a California king mattress. However, it must be understood that the headboard will not fit as well as a paired headboard.

Interior design websites often have articles on headboard designs, such as HouseBeautiful's "Best Headboard Designs" or HGTV's "10 Creative Headboard Ideas From Rate My Space."