Hi Chris
You need to be very careful at this point. Justification is the answer. Any extra tools are 'obviously' needed for household repairs, refurbishments, decorating, storage (the storage part being shelving for paint, wood, etc. no need to elaborate on what kind). NEVER refer to as necessary for anything to do with model boats.
Restyling the garage for your boat building comes under the category of 'a clear out'
Similarly with the loft.
The garden shed is always a good place (unless of course SWMBO is a keen gardener, in which case maybe the answer is another shed)
Spare bedrooms can often be referred to as 'The Office'. Stick an old computer in there which doesn't matter if it gets covered in dust to provide the justification of spending so much time there.
In reality this only delays the inevitable - SWMBO will twig it sooner or later, so you will need a slush fund scaled from a new dress/handbag/shoes to holiday/new car/house level depending upon how many models you have by the time she realises the scale of the 'new' hobby.
