Let´s say that you had a firm building architectural models (or any type of models) and you wanted to test the model building abilities of a person applying for a job.
You would ask him to build something but what?
It should be possible to build in one day or less.
It should be scratchbuilt

My pick would be a large spruce tree 1:100. Pretty difficult to do well.

What I would do:

1. Ask him of he ever joined any modeling contest and what prizes he received.
2. Ask him to show what models he had recently finished and his winning entries.

I would NOT ask for contest winning models.
Much of what makes a contest winning model, even in an AMPS/IPMS setting, is not what would be expected in an architectural model setting. Weathing, stowage, battle damage, judges 'eye candy'.

I would ask to see a portfolio of work and if I were serious about the cantidate, I would have a supply of materials and a couple of choices for projects.
Outdoor scene, building, street scene.

give a time amount (maybe even a tighter than usual deadline) and set the cantidate to work.

If you have 2-3 cantidates, then compare the work, side by side .
This becomes a comaprison of apples to apples as it were rather than contest winning planes/tanks/ships judged by different judges on different days.

If I were REALLY serious, I'd have the cantidates in some sort of a 'team project' , that way you could see who works and plays well with others. a prima-donna 'uber modeler' is great, but if they cannot get along with teammates and co-workers, they'd be useless.

My US$0.02
Mike

It really depends on the situation I would have to say. If it's a one day interview type of thing, I would have them build something that your organization does. Or has done in the past.

If the job was simply to build what they are told with set materials then hand them a box of materials to build 'a something'.

If the job is to be creative and fill a new need on projects then I would give them a box of various materials and the give them a scratch building task. See how creative they can get - example (very easy one)- give them wire and see if they can build a tree, or a sheet of poster board and see if they can build a hot air baloon.

One thing I like to do in my interviews is test thier ability to 'think on thier feet'. I take one of the hardest things that has challenged me in the last year and present it to them to see what ideas they can come up with in a short amount of time.