Just for a bit of closure, I went for it and had a go at a build using one of the Ferric Tang Band drivers I managed to get hold of (that's was a journey in itself). Finished late last night. Tested this morning. Wife came up to the attic just now: "The whole house is shaking, I take it that's worked then?" Yep.
For a n00b who's only tools were a jigsaw, drill and a whole lot of gumption - I reckon its turned out alright. I ended up having to cut it all freehand using the jigsaw, so sealing it was interesting. I've screwed it all together and used sealant rather than glue, so I can take it apart fettle the damping (if I can be bothered) and potentially swap out drivers in the future.
On initial listen it sounds fat and flabby, but very deep. Swimming in bass close to the decks, but thin a few metres away. My room is about as far from ideal as you can get for acoustics, mind. I'm using an old 100W p/c power amp and a cheapy active crossover to cut at 50hz (my Mackie HR624's have a steep rolloff at 50hz).
As a first tentative step in to the world of DIY speakers, and the first rung on the ladder to building a soundsystem, I reckon this has been a decent success.
Last edited by DaveDoe; 12-18-2016 at 02:58 PM.
Reason: edited: for spelling