For meter billing purposes, income and cost of goods accounts need to be created to record all meter billing income and expenditure.
On the ribbon, go to Accounts > General Ledger and create the necessary income and COGS accounts in the general ledger for the copier component of the business.
Something as simple as this might be set up:
Or perhaps more complex, like this:
Using these accounts, set up the appropriate Stock GL Groups for copiers.
Further information