Before I spend any time designing one? Thingiverse didn't really have anything that specific. Thought I'd check first.
That's a pretty specific combination. If you couldn't find it on Thingiverse, I think it is safe to say there isn't any yet.
Not quite what you asked for, but it contains a Pi4b and a witty pi L3v7.
the cable protruding from the case through the gap between case bottom and acrylic cover at the lower right is an adapter cable for the power connection soldered to the witty pi board. The red button is obvious. All parts incl. fan ready made from AliExpress.
Battery holder with single li 18650 cell at the top. Lower capacity flat cells don’t really cut it.
For the button I had to drill a hole in the aluminium case. A smaller button I had in my junk box fitted in the slit at the side where the battery holder is affixed with double sided tape, but it was a NC switch, and before too long I found out 😉