One thing to experiment with HHO is trying the Selfeggio frequencies through a pulsed generator for the electrolysis. Stan Meyer was using a pulsed generator of a specific frequency to generate more HHO then could be accounted for by the energy put in. His HHO generate was over unity.
Its not free energy but youtube has LOTS of videos on how to make your own HHO
I stumbled across this page which gives plans for making your own solar cooker. I want to try one of them (the easiest). It gets really hot here Down Under (Australia) - hot enough to fry an egg on the pavement sometimes. We also tried baking cakes out-doors when I was a kid, LOL, but that was not so successful (mainly due to not having a rapid enough directed heat). I was thinking about getting a small gas cooker (and the gas) in case of an emergency, but now my mind is thinking what about harnessing the Sun? I've got a solar powered torch and a solar powered watch already. Why not a solar powered cooker?