Scaling down (or up for that matter):

Question:  " Do you know of a method to change the scale of the models on your buildings from either the scale to HO or N to 15mm scale, I believe, 1:120 ?

Answer:  If you figure that N scale is 1:160 and your scale is 1:120 simply divide 160/120=133.33%
So print any N scale model at 133% and you should be OK.

Simple conversion matrix:

As each model may vary a little experiment to see what looks right to you.

Set printer to print off at:

Scale to scale->

[td]1:260 1:160 or 10mm 1:120 or 15mm 1:42 or  28mm [/td]
[td]1:260 --> 100% 162% 216% 619% [/td]
[td]1:160 --> 61% 100% 133% 380% [/td]
[td]1:120 --> 46% 75% 100% 285% [/td]
[td]1:42  --> 16% 26% 35% 100%[/td]

Here is a better format:

I mostly war game in 10mm so I rescale most every model down. I do play skirmish games in 28 mm however.