Twenty years ago I made a knock down camp saw out of some scraps of oak and an el-cheapo Sandvik bow saw blade. I used a length of mason's twine for a tensioner. Still have it, wouldn't like to do without it. I see the blades in hardware stores and home centers for a few bucks. Well worth the few bucks they cost.
When I tired of losing the tensioning toggles and jury-rigging 'em at Rondy, I smartened up, drilled a hole through one and threaded it onto the tensioning cord. Maybe some day I'll get around to making up a bag out of a scrap of canvas.
Nah, 's too much like work.
Three Hawks