Assuming you have setup your Inventory to be value in real-time (perpetual):

• Create a Customer called 'Internal Use'.  You will use this Customer to sell to yourself.  Optionally create a pricelist that sets all items to $0.00.

• Sell items to yourself as 'Internal Use' at a $0.00 price.

This leverages the standard Sales Order --> Deliver Order --> Invoice workflow in Odoo and means you sell, deliver and invoice yourself the same way you do a regular Customer.

The Journal Entries for a Customer Sale are:

STJ/2016/0001 represents the credit to Inventory and the debit to Inventory AR clearing.

INV/2016/0001 represents the debit from inventory AR clearing and the credit to Inventory AR clearing; the debit to Sales and the credit to Expenses/COGS. 

The Journal Entries for an Internal Use Sale are:

STJ/2016/0002is the same entry.

INV/2016/0002 only charges the value of the Inventory to Expenses/COGS.