Here's my helper holding the set up I use for on-the-fly closeups. It's not possible to use the smallest apreture for depth of field and hand hold the camera, so I shoot everything with flash. The diffuser is made of foam board and covered with packing plastic. It takes the small pin-point light source the flash makes and makes it much larger so the light is soft and wraps around the subject.
This is what it looks like (helper not included):

The lens focuses to about 18 inches (6x9 inch field of view) and at that distance the light comes from above or to the side depending on horizontal of vertical format. Focus the lens to the minimum distance, lean in until it's in focus and shoot.
For studio type shots I have a 24x18x4 inch box covered on one side with tracing vellum. It acts like a light tent, but more directional. No pic of that but imagine the box with a flash stuck in one end. It takes a 3 square inch light source and makes it into 430 square inches.