This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
Desiring to make a small piston for a model engine and not caring to make a pattern and send it away to have a casting made, I thought of using ordinary pipe caps, these being both in expensive and of a quality adapted to machining.
The cylinder bore was 1% in. in diameter, so I secured a standard pipe cap for 1 1/4-in. pipe which gave an outside diameter of about 1% in. The cap, not having sufficient depth for holding in a chuck, was screwed on a short piece of pipe and then trued in the lathe chuck. The outside surface was turned to a diameter of 1 1/2 in., then removed from the pipe, reversed and chucked again, and the threads bored out to reduce the walls to 1/8 in. This made an excellent piston for a single-acting engine.-Contributed by Harry F. Lowe, Washington, D. C.