Hi Harry, I think the engines only look a little complicated because of the fittings attached to them, ie lubricators (very important) gear boxs and pumps, strip that away and you get the engine shown under construction pic, which is the same engine as the one shown on the bed with all the bits. Only the Flash coils are welded, if you look at the coil photo you can see the joint which has been sleeved for strenght, I have the tubes welded for me as stainless steel welding (and tube) I'm afraid is beyond my capabilates. All of my boilers are copper and silver soldered, the tubes and bushes with "hard" siver solder and the end plates and end bushes with "soft" silver solder
All the bushes are phos bronze.
Phil