This is my modeling of a Molle Hook&Loop insert, based on Whiskey-two-four LoopAnyWhere insert. it's main use is for attaching a patch to molle webbing, but it also stiffens your bag/pouch which is great IMO.

Print or cut it, glue the hook fabric, and slide it between the molle webbing.

I've added a PDF with the dimesions I used, and a Solidworks model file.