Hi,
I loved your class and I'll produce a lot of them. For now I can just share a work in progress picture of some complete upcycling notebooks:

The ready made notebooks:

I just used your mesurements as an orientation, but just used the measurements, that came out when I folded my A4 paper into 12 pieces... It was perfect for using half pages of this little A6 booklet in the top left for the covers.
I'll keep you updated about the results...