Macro Diffuser designed for Olympus setup, 

you need some white opaque polypropylene (i use GBC PolyOpaque 0,3mm) as a diffuser material (just trace the shape of the diffuser and make some latches with a hole to attach it at the attachment points) for the attachment you need 3 of the washers 

for best results spraypaint the inside white, 

i print the diffuser with the cone first on the build plate but it has some issued with the attachment points on the bottom (0,2mm layer lines, pla+ on Centauri Carbon)

 i attached it with velcro on the flash and a rubber band on the lens (see pictures)