Exports - foreign exchange calculator

In this example you are a manufacturer based in the UK. All your materials are soured in the UK. You receive an order from a US customer who will only deal with you if you invoice him in US Dollars. The chart below models the effect that exchange rate fluctuations could have on your profit.

Receives order for (USD $):	$
Goods cost (GBP £):	£	View latest currency rates
Expected profit (GBP £):	£
Foreign exchange rate (Spot rate):	$	[?]
Time period to complete order				Exchange rate			Goods now worth	Profit (Loss)
Day 1 - you accept the order and start manufacturing product				$		[?]	£	£
Day 30 - you finish manufacturer, ship goods and invoice customer				$		[?]	£	£
Day 90 - customer pays				$		[?]	£	£