I've been looking into the possibility of building my own rebreather for several years. At first I wanted a completely electronically controlled closed circuit unit. Experience with homemade underwater video camera housings has made me rethink the wisdom of having life-support electronics in "waterproof" housings. A passive-addition semiclosed rebreather along the lines of the French DC-55 was my next idea. To start the actual building & diving process, I've constructed a basic closed circuit oxygen rebreather, probably the simplest implementation of rebreather technology.

But before filling anyone's head with visions of carefree, bubblefree diving, a few quotes relative to rebreather diving:

"Poor judgement is the result of a lack of experience; experience is the result of poor judgement." (Anonymous)

"Always assume your rebreather is going to malfunction at any moment."
"Never underestimate your capacity for doing something really stupid."
(Howard Hall, underwater filmmaker & 13 year rebreather survivor)

Here's sort of a chronology of my thinking along rebreather lines...

Closed Circuit Mixed Gas Rebreather

Passive Addition Semi-closed Circuit Rebreather

Closed Circuit Oxygen Rebreather

K.I.S.S. Inspired Closed Circuit Rebreather (First look at a work in progress...)

PO2 Monitor