SHIFT + ALT + X object mode
SHIFT + ALT + Y object mode
SHIFT + ALT + Z object mode
Use the Mirror tool to quickly set up a Mirror modifier on the selected objects.
By default, the selected objects will be mirrored accross the chosen axis of the active object.
If Mirror across Cursor is chosen in the Operator Properties all selected objects, including the active one will be mirrored across an empty positioned at the cursor.
Any number of mesh objects or grease pencil objects.
The tool will recognize DECALmachine's Decals and automatically adjust the Mirror mods to also flip the UVs
The Unmirror tool simply removes the last mirror modifier in the stacks of the selected objects.
Object Context Menu
This is an old video, there no longer is support for Group Pro groups.
Mirroring MACHIN3tools groups already works as you'd expect.