Trekking pole smartphone mount / selfie stick

Use a rubber band to prevent the smartphone from sliding.
When printing, edit width and length of p3_smartphone to adapt it to your smartphone:
100% is(depending on your printer, of course) about 65.8mm and 8.4mm, which fits for 2017 version of Samsung A3.
The wrench size for p4_knob is M5(8mm).

Let me know if it works for you.