Bought one of these today and reckon would make a good cheap billy can. Seem to be very sturdy although would need to make sure no harmful coatings.
http://www.diy.com/nav/decor/decora...al-Paint-Kettle-1-Litre-9254685?skuId=9262384
http://www.diy.com/nav/decor/decora...al-Paint-Kettle-1-Litre-9254685?skuId=9262384