I made this some time ago for a client, to do some testing for the actual part that will be made out of aluminium.
This is made to fit a certain diameter and I recommend you edit the Fusion 360 file directly to make it fit for other sizes because when you reside it you also modify the connection gaps.
Another option will be to only resize it on X and Y axis only.
Print part 1 - 2 times and print part 2 - 4 times.
Check this wiki for more details on the subject: https://en.wikipedia.org/wiki/Static_mixer
I have also attached some pictures of the metallic component made by professionals.