It’s as simple as this for each db you want a copy of. Just run it from the master db. This works if you want to make a copy on the same server. If you want to make a copy from another server, you would have to connect via PowerShell.
Click through for the T-SQL syntax. I’ve used this before on some reasonably large databases and it can take a while for that copy command to finish, but if you’re feeling impatient, you can check the status of the job using sys.dm_operation_status.