We did a lot of water rockets at the cabin last season but were always limited by the compressor up there. It would only generate 80psi or so. After reading about using electrolysys to make hydrogen / oxygen for rockets in my make magazine I thought I would give it a go.
For the electrolysis I used stainless steel outlet covers on stainless bolts. I kept them seperated by nylon spacers. Two sizes if spacers kept them apart as well as protect the bolts from touching the plates they went through.