Thermite has to be one of the most forgiving formulas there is. When I was a kid back in the sixties, we made thermite by wire brushing rust off of everything we could find in the garage (we had to anyway as part of our chores), then we filed down aluminium drink cans until we got enough. We used a home made balance to get the weight proportions right and aquired some chemicals and magnesium ribbon to light it. We mixed it by shaking it in a small paper bag and ended up with a pile about 2 times the size of a fist.
It worked like a charm. It melted through two 25mm steal plate and a little bit into the ground and left a slug of iron behind.
Phil Blackwolf