Cut object in half leaving both pieces with a face

Support Basics & Interface
1

I selected these vertices around the leg and want to separate the leg (upper/lower)
How do I do this? like so; https://i.imgur.com/rnl9gEY.png

2

with a nice loop selected, press V to “rip” them apart.

if you need a specific shape, such as for 3D printing, then i suggest you get into Boolean.

3

or use the bisect tool

happy bl