I modified the third hand posted by Cybertron3D to adapt it to this alligator clips:
https://www.amazon.it/gp/product/B00O7P0ZS6/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1
and to some magnetic balls I had at home to make the base heavier and the stand more stable. You will find a hole in the base to fit something heavy of your choice.

I included the f360 file but it was my first time using it, I usually design in Solidworks, so the file is badly organized. I'm sorry!