Shepherd's whistle
They are also produced commercially. Simple whistles may cost less than 1 USD in bulk; expensive ones may be quite ornate. They are commonly made of plastic, aluminum, stainless steel, silver, brass, titanium, Corian, jade, buffalo horn and other materials.
Windscale Piles
A single reactor was costed at £20 million, but two could be built for between £30 million and £35 million. The number needed depended on the number of bombs required. In their report to Attlee on 1 January 1946, the Chiefs of Staff recommended that two be built, but for the moment it was fixed at one reactor capable of producing 15 bombs per annum. In his address to the House of Commons on 8 October 1946, Attlee referred indirectly to the decision to build the piles: