The UI script is in both Blend files. You won’t see anything in the Start one, because you have to setup the bone collection and setup the custom property of rig_id on the armature tab. it needs to be set to ball_rig and yes it is case sensitive. You can go to the text editor(Shift+F11) and then click the text drop down(To the left of the new button) and select ball_ui.py
