Preheat the oven to 180C/160C Fan/Gas 4. Grease two loose-bottomed 20cm/8in sandwich cake tins and line the bases with baking paper. Place the flour, sugar and baking powder in a large bowl.

But a lot of the hard work in making a tube chassis is taken care of with the cake tin design, and the result looks rather professional. We have something of a personal interest in single-ended ...