For Bob Hoffman, what began as an simple desire to get a couple of customized beaded harmonica cases to match his outfits turned into a huge collection of intricate and originally handcrafted cases, one of the largest of its kind in the world.

The Washington D.C. resident took up playing the harmonica when he was in his mid-50s, and it wasn’t long before collecting specially designed cases became a more serious pursuit than the instrument itself. Over 15 years, he has collected more than 500 cases, created by nearly 450 different artists, and earned himself the name “Hoff The Harmonica Case Man.”

He commissions the cases when he meets artists at fairs and exhibitions all over the world, and every case is personalized with the word “Hoff” or his image included in some form. While each holder is unique, they can all be worn around the neck and they are designed such that the instrument can be easily accessed—Hoffman’s criteria.

The boxes are constructed out of many different types of materials, including wood, glass, metal, beads, eggshell, fabric, plastic, and even ivory. Some of the designs have themes, such as “things that move,” or Vermont, where Hoffman spends his summers. One of the highlights of the collection is a Lincoln-themed case, with the last picture taken of Lincoln printed on it, along with an image of the gun used to shoot him.

Hoff showcases his unique collection at different exhibitions as well as at his home in Washington. He also recently published two books with photographs of the cases.