I don't relly understand what you meen here. If you speek about the strip foam there was not a lotof loss in material. The Tabby was built from two sheets 1.2m by 2.4m 15mm thick.
I ripped the strips with a bandsaw with a very thin blade. As the strips are only 5mm thick there was no routing of the edges.
The total cost of foam (Airex) was about 150 USD.