I only have occasional asthma attacks, so my inhaler lasts a long time.

In fact, it lasts long enough that the cap becomes loose after a while and comes off in my pocket.

So I printed a slightly smaller / tighter cap.

In the pictures, the orange cap is the one that came with the inhaler and the "natural" one is the replacement I made.

Update June 2019: After a while, the replacement cap became loose as well. I reprinted, double the scale in the z-direction only, and that cap seems much tighter than the first. Don't have time to upload a new version right now, but modification should be easy enough with every slicer software which which I am familiar.