A smartphone holder you can mount on the X axis belt tensioner to monitor your printing process. It is made out of 2 parts, so you can design your own thing.
For this type, you will need 3 10X5mm neodimium magnets and some electrical (rubber)tape. The tape is required to increase the adhesion of the smartphone to the printer.
Changes on the V2 version:
Screw and nut: M4, 45mm and DIN557 GB39 M4
https://www.aliexpress.com/item/4000075591731.html?spm=a2g0s.9042311.0.0.27424c4dmNbeOq
https://www.aliexpress.com/item/32875607040.html?spm=a2g0s.9042311.0.0.27424c4dmNbeOq
The author marked this model as their own original creation.