Having a lowered Venetian blind on a door will swing back and forth when the door is opened or closed. A solution to fix that problem is build a box about 2 inches deep and about 2 inches wide. The box will have a bottom and one side with the ends enclosed. Mount the box on the door at the desired location at the bottom. Once installed only the top of the box will be open.

Lower the Venetian blind down into the box and it will not swing back and forth when the door is opened or closed.

I done it on our back door some years ago. Works fine for me.