Take one lump of cast iron. Apply expertise. Lots of expertise and plenty of TLC. Stand back and admire finished cylinder barrel, fins and all. (Instructions only apply to people named Humbernut!)...

I thought you all might like to see what can be made from a lifeless lump of cast iron, all for the princely sum of £28.

It beats autojumbling any time, and you are guaranteed a standard bore and not a plus-60 job!

The photos show the barrel more or less as a lump of cast iron, then there's one of the fins being cut, and finally the finished article alongside the real thing.

So has anyone else built a bike from first principles?