I was thinking on this a little more last night.
We should also input the scale for the models, because things like dystopian wars are actually 2mm but would be good to have. This also opens the site up to having 28mm , 54mm ect which would generally increase traffic and interest. I don't see any reason not to have them

we can actually populate the relationship matrix quite quickly. The site can automatically add one point of similarity to stuff of similar scales and from the same manufacturer.
As well as people doing a few comparisons when they visit (that'd have to be the front page I think), can also build a list of likely similar models based off X is similar to Y and Y is similar to Z therefore X is probably similar to Z.
Mathmatically, expand the relationship matrix by itself to get a 3d matrix, each cell holding the product of similarity score XY and YZ (for example). Initial sort of theses values can drop any that are zero or less, and the remainder can be sorted in value order, giving a list of 'likely similar', that can be served up in order to the 'Compare' page
Say this is done daily or every hundred comparisons (Not too often, it's computationally heavy) it would allow the similarity network to be built up much faster then just random serves.
Even with basic google analytics, it'd give the owner insight into popular search terms for models, and visa exit pages an idea of what models are actually selling. It wouldn't be too hard to utilise the database itself for even more in-depth analytics. Basically, it should pay for it self.
I don't have time to build this. I really don't. But for someone in tech (Hena?) or model making (too many

) it might be a good investment...