Remixed to fit on the original spool holder of the Ender 3 v2 (and maybe others).
It fits nice and snug to on the hole of the spool holder. Simply slide your sensor on the frame and clip it.

I used this kind of sensor https://www.amazon.fr/gp/product/B07XG2PTH8/ but you can find it on any sites.

I printed it on the back, the legs on the bed with supports.