I'm an active participant over on the Earbuds roundup thread (http://www.head-fi.org/t/441400/earbuds-round-up) and recently there has been a fair amount of discussion regarding DIY. I realize there is already a thread discussing IEMs, but I didn't see much discussion for ear buds.
There are a lot of components available for sale on AliExpress, but unfortunately the product descriptions are very often lacking in detail. I'm hoping this thread will become a place to share information on parts, show completed builds, give impressions on tuning materials, potential pitfalls, etc.
Just to kick off the discussion, I'm planning to build a 300 ohm earbud with these drivers (thanks to @Brian Coffey for recommendation):
As well as what I think is a Yuin PK1 type bud: