Hello,
maybe a silly question but... for the mold below what shape would you recommend for the bag?
A big rectangle with of course more pleats on the shorter sides of the mold or try to make the bag similar shape of the mold (of course bigger to allow for pleats)?
Thanks

I agree with the big rectangle - maybe try orienting it along the bounding box of the mold.  Lots of pleats. Also putting the sealant tape on the perimeter of the bag first will make it way easier and faster!  Forming pleats becomes quick and flexible and it only wastes a little sealant tape.