I wanted a macro flash diffuser that was a bit better than a pringles can but would also not break the bank so I designed this one. It's designed to fit a Nikon F100 film SLR camera using the Laowa 100mm f/2.8 2x ultra macro lens and the Nikon SB-28 speed light but may fit other camera and flash combinations. I printed this using PolyTerra Charcoal black PLA with a .2mm layer height, tree supports, and a 25% infill. Printed with the top of the diffuser laying flat on the bed. I also designed some clips the clip the diffusion material to the front of the diffuser. They are intentionally a bit loose to work with a variety of materials. My solution to tighten them up was to use a strip of gaffer tape on one side of the flanges and it works like a charm. For reflective material I just used aluminum foil tape like what you can find at most hardware stores. The diffusion material pictured is regular parchment paper like you would use for baking. To mount the diffuser to the camera and lens I used two #64 rubber bands (8.9cm x 0.6cm) 

Key dimensions:

overall length: 200mm(from back of flash socket to front most part of diffuser)

Front width at widest point: 200mm

Flash socket: 68.47mm Wide x 41.96mm High x 20mm Deep 

Distance from front of flash socket to front of lens saddle: 83mm 

Width of lens saddle: 10mm

Lens saddle radius: 36mm