For the TGO Challenge in May I made my own potcosy and a bagcosy. I used radiatorfoil, ducttape and aluminiumtape. The bagcosy has an 'envelope form' and can be closed to retain heat for a longer period. The bagcosy has a wider base so the 'boil-in-the-bag' meals can stand up inside. Don't want to spoil it on the tentfloor, do we ?
The potcosy has a double layer, a base and a top, to be able to seal of the cooking pot as much as possible. There's an open space where the handle of the pot comes out. The potcosy is for meals that are made..... in a pot, yes. After bringing 500ml water to the boil I switched of the gas and put the pot into the cosy. Twenty minutes later the meal was still piping hot so the test was a great succes.
The bagcosy weighs 23 grams and the potcosy weighs 35 grams but will save me a lot of gas.