If you think the foil is fair spray it with a high build primer and then wet sand with a cork block and 1200 grit until it looks flat and shiny with no dimples. Look at the reflections. They must all have clean straight lines. Then spray a top coat and wet sand again. I went 800 and then 1200 (don't press too hard with the 800 or you will have probs removing the scratches it makes) and then cutting compound. I would have liked to go over with 2,000grit but couldn't source it at the time. I was making the plug for the rudder on my Tri. There is a pic in a thread on Farrier tris. I started off by getting the reflection of the trees to look straight and eventually got the extremely fine lines on the diffuser of a hand held fluro light to look spot on. Then I felt that I was in the ball park.
Someone mentioned the word ZEN. Forget about the time it takes because it is all about getting it right.Suspend time and get into the zone to get it right. If you don't think you can do that just buy something off the shelf.