I'm going to throw something ad hoc in he

My old man kept all his steel tools in a big wooden cheast of drawers in a
mouldy damp garage with a non DPC concrete floor.

Wind howled through both door frames and the window was dodey, though there
were no liquid water leaks.

The tools, including planes stayed in near mint condition.


The chest was heavy (2' x 4' x 3-4' high and 3/4" thick wood. The drawers
were close fitting and the inside bare.

It was his theory that the wood acted as a buffer taking in free water in
preference to it condensing out - also the wood did have some insulation
value.

So perhaps a wooden cupboard for tools - real wood or thick ply, painted or
varnished on the outside, bare inside and well sealed (close fitting or
draught strip)...

Also, if using a small instrincally safe heater[1], or dessicant, they will
go a lot further in a small sealed space...

I realise if the OP wants a trainset or large tools to be protected, this
won;t work, but for all the small and power tools it could - and an
excellent inscentive to put away

[1] RS have some small ceramic low temperature heaters that are supposed to
be instrisically safe (in the way that an oil radiator is).

--
Tim Watts