Are you using Production Management or Operations Management to produce your items?  What version and Product Update are you using?  When you say 'manufactured at no charge' do you mean no charge to the customer?  If you are building an item it is reducing your Inventory quantity on hand so it is still going to be a cost to you so I am not sure zeroing out the item cost is the way to go.  I think more information is needed to answer this question.

Yes, no charge to the customer. There is obviously a cost to us, but we are still working on building out the operations management module to capture these costs. We are most concerned of how we can capture the sales value of these no charge to customer orders?

What's wrong with a zero dollar invoice? 

• If you want, add a /FREE charge line with a negative amount to track the invoiced amount to a GL account of your choosing (posts to CoGS, Revenue, and your chosen GL account). 
• Or just override the unit price of everything to zero (posts to CoGS).