How to Use:
Drag the Prefab included as is shown in the video to the root of your avatar
Make Sure the "Player Tag Grab" and "Player Tag Object" are at "1" scale
Copy all the contents of the FX controller included and put them in your avatars controller.
Make sure the Parameters "GestureLeft" (Integer), "Tag_IsGrabbed" (Bool), "Tag" (Integer), "Tag_Height" (Float), "Tag_Scale" (Float), "Up" (Float), "Down" (Float), "Left" (Float), "Right" (Float), "Forward" (Float), "Backward" (Float) are included in your controller.
"Tag_Scale" (Float), "Tag_Height" (Float), and "Tag" (Integer) are included in your avatars synced parameters.
Add the included Menu to your avatars Main Menu as a Sub Menu.
After that, to use it: Enable it in the menu. Then left hand "fist" brings the tag to your hand, left hand "open" releases it. Finally, Upon Player grab, it disables the proximity colliders temporarily for 1.2 seconds to allow one player to attach it to another.

Requirements:
Latest VRCSDK3
VR Labs World Constraint: https://vrlabs.dev/item/world-constraint
Unity 2019.4.31 f1