Someone I know (not me) has recently had problems with bed bugs. I have advised him his best bet is to (1) Buy a kick-ass steam cleaner and nuke the brutes from orbit, (2) get a professional pest controller in, and (3) Stop buying second hand furniture in future!
But being an inventive sort, he prefers a more subtle approach and is now intent on designing the perfect indoor bed bug trap.
It appears these critters are attracted by a localized $\ce{CO2}$ excess and by body heat, and are repelled by light and (presumably) excess heat. So assuming this trap won't involve a tethered goat or suchlike, he will need a compact, non-flammable, non-toxic, readily and cheaply available substance that can be persuaded to release a steady stream of $\ce{CO2}$ for several hours (without releasing CO or any other noxious or smelly biproduct).
I was thinking perhaps water dripping slowly onto calcium carbide, if there was some way of converting the resulting acetylene to $\ce{CO2}$ without burning it at a readily discernable rate. But a "slow burn", if it could be attained, might provide the heat source (although I reckon a more controllable electric heater would be better for that).
Any ideas? I suppose one obvious answer would be to simply buy a $\ce{CO2}$ cylinder, but could one then buy a sufficiently slow release valve to go with it?