In article
R.P.McMurphy wrote:
Hi all, I need to heat a steel rod 12inches long and half and inch in
diameter up to around 40 degrees centigrade and keep it within 2degrees. It
will need to be kept constantly at this temperature. it can only be heated
at one end, the other end needs to be un cluttered.

Any suggestions how I can do this?

Heating at one end means the other end may be significantly cooler
unless it's insulated, amd presumably insulation counts as clutter.
Copper would be a better choice as it would heat more evenly because of
its better thermal conductivity. But you haven't given many clues, such
as what's happening at the other end.