Note:
We have no stand-alone manual for 8 m² or 10m² Scheffler Reflectors ready.
Mostly people learn how to build those sizes of Scheffler Reflectors through a course.
You are welcome to download the manuals on 2m² or 2,7m² Scheffler Reflectors here.
In any case:
even if you actually wish to build the bigger reflectors but can not organize a course right now - it will be helpfull for you to start small and build a 2m² or 2,7m² Scheffler Reflector first, because the techniques are very similar, but the the smaller reflectors are easier to handle and the investment is less.