This is a lid for a baby food jar that can be used to make a fruit fly trap. I put a splash of apple cider vinegar into the jar, then snap/screwed this lid on (I measured it to be a tight fit). It happens to be in a format the customizer won't choke on, so go ahead and play with it. The values that worked for me are already loaded as defaults.

We had some apples that sat on the counter too long. Sure enough, fruit flies. And it's been a week now of these damn things. I glanced at the options to download/print a trap and I just got bored. Didn't seem like any less work to fiddle with someone else's design for such a simple part. And hell, I've been feeling depressive, so maybe an easy little project would cheer me up.