A while ago I published this :
Description of an assembled noninvasive capnography setup.
Here is an earlier draft of the article that is open access for you.
AN ASSEMBLED NON INVASIVE CAPNOGRAPHY SETUP – A FEASIBILITY STUDY
My mate Dr Reuben Strayer recently published his own approach to DIY mask capnography here
Obscure author? Cheeky bugger
Prehospital and Retrieval Medicine - THE PHARM dedicated to the memory of Dr John Hinds 