I planned out what I would need for the army using The Nutcracker lists on Kaptain Kobold's blog:
1 x Behemoth General (1 big rodent plus a couple of bodyguards)
10 x Warband (30 smaller blade-armed rodents)
As I said earlier getting hold of armed mice is very difficult so instead I used an IM giant rat (it might actually be an upright wolf but it looks the part) and 30 of their 15mm Ratman Swordsman (FRAT1).
I did the usual file thing on the figure. Got his base nice and flat and cleaned up mold lines. IM figures are often flash free, which is nice.
Looking at pictures of The Mouse King he is usually dressed in a coat or cloak with a belt and scabbard for his sword plus a crown. I decided on a cloak rather than a coat because I felt it would make the figure look bigger and I could put some dramatic billows in it. I made the cloak out of green & yellow putty rolled together. Then flattened into an approximate cloak shape before fitting to the figure. I then used a cocktail stick to work into shape around his neck and to create the heroic billows and folds. I made his sword belt out the same putty.
Next came his crown. I'd already tried a small piece of balsa but it ended up looking like a badly fitting fez. So, once again, the putty came to the rescue. A small blob on his head was worked, pushed and teased into a crowny shape. The king's crown is adorned with gold mouse heads which I had no intention of even trying to reproduce. Instead I cut down four dress-maker's pins and pushed them into the hardening putty. I used my trusty cocktail stick to close up the putty around the pin shafts.
Finally his sword. Once again a cut down dress-maker's pin was glued onto his left-paw and a hand-guard made out of a small piece of putty. I then put the figure on top of a radiator to help the putty harden off.
Here are some pictures of the re-modelled Mouse King (without sword and belt):
All the best!