Info on tuning cotton, horseshoe tuning foams and manipulating the sound.Don't worry about doing that, just thought if you knew off the top of your head that it would help narrow down which one I want to build next. That's a good point, are there any posts about how different parts such as adhesive foams and tuning papers affect sound? Or does it just depend mostly on the driver and shell you're using?
I completely agree about learning from your mistakes, my problem is that I'll work on something way beyond when I should've stopped and said that what I wanted to do wasn't going to work. Your builds give me more confidence that I won't get into that situation and your tuning preferences reassure me that even if one of your builds isn't exactly to my tastes it won't be to the point where I dislike it or be unable to stand listening to it.
Here's more information about tuning.
Tuning becomes a bit easier if you understand this basic information. The rest is up to you to have fun and experiment. You'll definitely learn as you go.
Drivers and shell synergy are important in how your buds will sound and need to be tuned. AFAIK, the only way to find good driver and shell combinations is through trial and error.