I designed and built the stand below to handle the 1-1/2" scale locomotive that I am building.  It adjusts from 17" to 37" in height.  I used angle iron for the rails but anything available can be used.  Five inch wheels are used in the drawing.  Any wheel size can be used as long as they can handle the weight of your locomotive.  The three sections of pipe were "turned" on my lathe for a good fit.  These legs were welded to top and bottom plates which were then bolted onto the rail and wheel sub-assemblies.  This allowed me to disassemble the stand for easy storage.