OK, here are pics of a few builds:
First two pics are 3 systems in our bedroom (taken some years ago to judge by the TV!). Left to right: Bigger Is Better (BIB) variously referred to as a tapped horn or a pipe horn using Mark Audio Alpair 10M driver; mouth faces the ceiling & uses ceiling & walls as extensions of the horn; because the BIB uses the room as part of the horn, I get a flat octave from 25-50 Hz, something I have never seen before 'in room'. Center is a variation of Martin King's small passive open baffle. Right is a Dave Dlugos design: Fonken Prime (Fostex Onken) using Fostex 4.5" FE127e; sitting on stands I built which have shelves for CDs.
Next two pics show a Metronome design (left) using 4.5" Fostex F120A drivers (I wanted to find out about the 'magic' of Alnico) and a transmission line using 8" Fostex FF225wk supplemented by an Eminence APT80 horn tweeter.