Off the shelf weight sensor to detect cat in a litter box?

Hardware
1

Motion sensors aren’t working because they detect light and shadow changes in the room despite the motion sensor being on the inside of the litter box facing the back wall. I can’t tweak the settings of the sensor, so I think a standard PIR just won’t do the job.

So, weight sensor? Place under litter box, weight until it detects sudden weight? I have no experience with weight sensors at all but it seems like if it can detect a human getting into and out of bed, it can detect a cat getting into and out of a litter box.

I don’t want to solder or put together parts from China. I’d prefer ZigBee/Z-Wave over ESP, but I’ll take what’s available and cheap and doesn’t require too much from me. Suggestions?

2
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I take it that’ll require some soldering and an ESP? I have seen these but was concerned they may be too tall. I couldn’t find height measurements anywhere to confirm.

The FSR style may be closer to what I need, but just as in the DIY area as I’m expecting the load sensor.

4

An ESP yes, but the soldering is not necessary. A crimp connector can do it also.

The pictures does not show height, but the second one does show the other length and it is not that big, so probably not that tall too.
The one I link to is for a 50kg version, which might be too heavy for you, but there are alternatives on the page too.