Tech Bcd?

[Omicron]

Lego is a good way to put it

You start with the plate.  From there you add a harness - you can either buy a deluxe harness that includes snaps on the shoulders, chest straps and that sort of thing, or you can just thread some webbing throughout.  Both options are available from diving companies.

Then comes the wing.  The wing is actually bolted to the metal plate via a single tank adapter (an angled piece of iron that a single tank sets against). 

They really are a joy to dive, and no more difficult than a normal BCD.