This is a brief overview of the general design of the BIAB bags I make. Obviously they are custom made to your specification, so the design can be adjusted to meet your requirements.
Bags are designed primarily for function, rather than aesthetics (although, I do my best there too).
The inside seam of the bag, the one that comes into contact with the grain, is smooth, and has been turned and top-stitched, this is to provide as few areas as possible for grain to become caught, and to make sure the bag is easily cleanable.
The outside of the seam looks slightly untidier and you may see thread from the stitches at the edge, this is the side of the seam that has been overlocked or serged, to provide strength. It may look as if your bag is inside out, it's not!
The drawstring on the bags is made from 100% nylon and is heat sealed at the ends to prevent fraying.
Bags have a plimsoll or depth line marked on them. This level is a few cm shorter than the vessel depth or element height that we are given. If you place the plimsoll line on the rim of your vessel and then tighten the drawstring, you will have a visible gauge to ensure that your bag is kept safely away from the element or bottom of your brew vessel.