Hi there.

I'm not online at the moment but my setup is more or less similar to yours. Knowing when to use the abilities at the appropriate times aids with higher results.

I was able to create a pair of Avengers today, but during the process I felt as though I was simply getting lucky. The highest I was able to get was 75%HQ on the easier synths (and this was not guaranteed, it usually ends up being a little lower), and for the Darksteel Ingot and Flawless Grips I believe I scored only 50-60%. The Ingot is tough because as far as I can see, there's no way to get HQ Coke so your quality starts painfully low. For the Avengers, I went straight into elemental instability near the beginning and was only able to get 14%HQ.

Generally speaking, it seems to be quite unlikely to score less than 50% on any of these synths. I didn't encounter any severe elemental instability for 20 material synths, the only time it hurt me was for the Avengers. I'm doubtful there are any other methods that are significantly better, but I'm open to ideas.