Hi Brian, another couple of things - this corner here:



Does not actually come down to a straight end like it looks, it is bent into a really tight corner at the very bottom of it (shown here zoomed in on that corner):



Really tight bends like that will tend to interfere with filleting as well.

One other thing I noticed was the arc pieces on the inside were actually like 186 degree arcs so there is a kind of slight angle between them and the lines connecting between them, instead of being tangent.

I'll cook up a tuned up version for you in a minute.

- Michael