Tim, I switched from the diffuser dome that came with my Nikon SB-800 flash and use a much larger one from Vello when I want to use that flash. They make them in various sizes I believe.
For most of my macro work, with a Nikon 200mm f4 Nikon lens, I use the Nikon SB-R200 flash with a small Vello diffuser. I do not attach it the way it is shown at the link below, as I have another flash bracket that gets it off the lens and close to the subject. But the Vello diffuser works much better than the dome clip on diffusers.
https://blog.sigmaphoto.com/2012/top-ma ... rt-otoole/
I have a friend who uses various flash products made by Expoimaging . Two possible products are shown below.
The first one is the Rogue flashbender 2.
https://www.bhphotovideo.com/c/product/ ... ector.html
The second one is smaller and has a diffuser cloth that can be added.
https://www.bhphotovideo.com/c/product/ ... _soft.html