Summary

This DND initiative tracker includes a couple small magnets to hold the top indicator instead just pressure.
It is based on this coold design: https://www.thingiverse.com/thing:4130591 by https://www.thingiverse.com/unsoluble

You can use small 2mm x 1mm magnets on each side. I used these ones: https://www.amazon.de/SBS%C2%AE-Neodymium-Magnets-Extra-Strong/dp/B01ARLYHGE/ref=sr_1_18?dchild=1&keywords=magnet+3mm&qid=1598959677&sr=8-18

Wanna play around with the original design made on onShape? Here it is!
https://cad.onshape.com/documents/86263bd55085a015fdc27f32/w/3be6e70b442a2a13b95f38d5/e/53fc18a84b870dbc7c27c028