Wilesco produce thrir roller and traction engines in kit form, painted
etc., just screw together. about £100
Mercer produce a complete kit for a traction engine in approx 16mm
scale. No machining required, just painting and assembly, but you then
have scope to turn your own custom parts, such as a solid flywheel,
and modify it from meths fired to gas as you see fit.
It is actually quite a nice little engine, although mine seems to
vibrate out of gear when running round the garden. Expensive though,
about £350 for the basic kit.
Geof Winwood is the agent
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There is a link to an "Old Glory" Review of the kit.
I would suggest one of these as a starting point, before embarking on
a scratch built engine such as Minnie, or a 1 1/2" Alchin type, my
Minnie castings have been in the box for 18 months :-(
Martin L