Hi!
In order to make my life easier in optimising the shirt plackets (button, buttonhole, sleeve), I implemented a placket generator. It is completely without documentation, but if you made or used plackets before for sewing, you will recognise most of it, and the rest can probably be inferred or guessed. So maybe it is useful. Here it is:
The reason I made it initially was to move the buttonplacket further under the buttonhole placket, to help hide it better. Now I also use this for the sleeve plackets.
The generator can also do concealed buttonhole plackets, i.e., with an additional fold to hide the buttons.
HTH
Henrik