Help Rope help? How many mm? How long? What specific material?

[SpaceAlien]

For short drop using a tree.

 

[Darkover]

Any rope that is sold at a store should have a weight rating on the label.

 

[Praestat_Mori]

Afaik round about thumb think (1/2 inch), dock line is suggested is best, use the search rope questions have been asked many times.

If you haven't read this thread about trees, there's useful info about trees:

Trees to use for hanging - from a tree expert

This thread is ONLY for those who 1) must do partial/full suspension hanging, and 2) can only resort to using a tree. I was a professional tree climber and trimmer for 5 years, i trimmed/felled trees away from powerlines all over Wyoming, Utah and Idaho. Just thought id give my best insights...

sanctioned-suicide.net