I set out to try my hand at scratch building a locomotive, well, at least to partially scratch build it.  The locomotive will patterned after a Class A Climax and with a trailing car for water & fuel.  The steam engine will be a butane gas-fired 2 cylinder kit from Graham Industries.  A number of the components, like valves, the gas canister, lubricator, steam pressure safety valve, the butane burner, and the pressure gauge will be purchased.  The rest I will make from either procured castings or from scratch, including the locomotive & trailing car frames, cab, the boiler, a 2 speed gearbox/transmission, the smokebox & stack, water tanks and fuel enclosure, the power bogies and trailing car wheel sets.

Here's my builder's elevation drawing I am following: