Let's say you want to create a handful of metrics for a client to update on a daily basis. Something like number of cars in the parking lot of their store or number of high fives given by happy customers (man, really hope this one is a real thing for you!).
To do this, you'll need to add a user-defined metric to a table and train your client on how to flip cards and input data.
Bring your dashboard into edit mode, select Metric > By Metric Name > User Defined Metrics
Select "Create User Defined Metric" and fill out the required fields:
Select Save and you should see your new metric listed. Add this metric to your table like you would any other metric.
You now have a completely new metric to work with in a manual table!