Step 4, Prehensile Top cap install.
This is really just to stop water getting into the steerer and look nice. I was thinking of an expander plug, but star nuts are so cheap. I got 1 inch and 1 1/8th inch star nuts and checked which works better. The 1 inch one looks the best fit, so pop it in and hammer away!
I then measured the amount of empty un-spacered steerer and bought some carbon 1 1/8th spacers to fit, with a flared one at the bottom.