Glad somebody else noticed the "too dead" problem.
As far as DIY... I made mine from some Roxul board. Triangular for all four upper corners, and some straight pieces for the tops of the bookshelves to run along the top, but stepped at the height of the ceiling as it increased further away from the speaker corners. I also had placed thick wool blankets (neatly folded - WAF) up there as well. As it turned out... the room went from "live" to very "dead". It was very noticeable, particularly at low volumes. I don't "crank it up" very much, and the room was so "dead" I lost the "sound stage" effects at low volumes.
The room is only 17' x 12', has a "splayed" ceiling starting at 7' and ending at 8.5'. The long wall at the 7' height is "empty", except for the Klipschorns in the corners and the Forte's. I ended up removing bass traps except for the 12" tall ones in the far wall corners and a diffuser/ absorber piece along the upper back side of the rear wall, ended up changing the "throw" rug with another one to get the "man cave" to come back to life. The splayed ceiling geometry, coupled with the bookshelves and the equipment rack system on the three other walls apparently do not need the bass trap treatment I had originally guessed would be required. I also have removed the new throw rug altogether and the room sounds very good, very "live", but not too "bass" resonant, so as it stands, I'm probably going to go with a very small rug in the center area opposite the outside exit door.
He has truth; the wheel of time may roll whither it pleases, never can it escape from truth. It is important to hear that such have lived. All Hail Hypno Toad!!!