Pretty simple, assuming each fin has the same spacing.
Extrude the flat parts first, cut to the correct angle, then sweep the end profile up. Pattern it to get the number you require. See the attached file.
tapered extrude.SLDPRT.zip 98.7 KB
Thank you so much, this is very elegant and in the end pretty simple like you said.
Had a go using surface loft between two profiles,
copied your bottom sketch to new height plane then loft and thicken,
had to delete few bad relations/dimensions on top sketch to make smaller, not fully defined yet
Wow thank you for the effort, I knew how difficult this method was going to be. I think Logan's method will be easier to use though, especially if you needed to change the angle of the tapering.
I appreciate your help,