Boards
Weighing yourself before and after you take a shit.
is a good way of finding out the weight of your shit without getting your hands dirty.
If you want cubic volume fill a bowl to the brim and place it within another larger bowl. Hover over the smaller bowl in a position that would allow the easy flow of shit. do the shit. any water that flows over is the cubic volume of your poo. Measure it . job done. post results.