My wife did not want to keep having to buy new clothes throughout the early months of pregnancy as she started developing her baby bump, so I swung into action!

Made to loop around the existing button on your pants/jeans and extend to the button-hole. File is parametric with 4 simple to use parameters. In Fusion, click the modify tab then go down to the bottom “change parameters” and stretch as needed. Simply extending the length a bit every week or so seemed to work wonderful for her, accomplishing it's task without breaking or adding any extra bulk. I have added a few generic length stl's in case you really don't want to use fusion.

Printed in TPU as its designed to be stretchy. I used a .6MM nozzle and .3 layer height and they printed fine laying flat with no supports in under 20 minutes each.