My DIY CO2 is doing all right, although it does not produce as much as that of some other people I have read about. I currently have two bottles running, changing out one every 10 days.
What I'd like to experiment with now is making a homemade non-electric diffuser.
I am in the same situation. Now I have hope that what I am planning will work. I have been told that a bottle needs to be changed every 3 days. I won't be able to that. Thus planning to do 5 bottles for 29G tank.
I have seen a few DIY Co2s with the small ceramic diffusers, which are just a few dollars at Ebay. A few I have read have not been able to build up enough pressure for them.