Tower rather than desktop or HTPC form factor.
uATX or mini-ITX motherboard
emphasis on quiet rather than cooling
I'll use a Sandy Bridge i3 2100 or i5 2400 CPU and integrated graphics
I'll start with
room for 1 DVD full height (drawer) DVD drive
room for a 2.5" SSD
room for 2 3.5" hard drives (5400 Western Digital green drives. 3 TB to start.)
bottom mount for an ATX power supply with intake from outside and exhaust to the outside.
I'll probably use a Seasonic SS-560KM for the modular cables, low ripple and fanless operation at low power. Way more power and weight than I need but I'm not aware of any first rate low power power supplies.
One well placed large diameter case fan should be adequate.
I'd like to keep the case light (and small.)
I use an Antex Solo case on a dedicated MusicPC and find it heavy to lift.
I use a Seasonic S380 power supply in that PC. It is quiet but not quite silent in my application.
The LIAN LI PC-A04B and LIAN LI PC-A05NB cases look possible but the thin aluminum panels might be a problem.
The Fractal Design Mini looks like a well thought out case but it is bigger than I need and heavier.
I took an image of the Fractal design Mini and modified it to reflect one way to get what I want.

I'd appreciate any leads for a small uATX tower case that would fit my needs. Thanks.