Sugar mice are made from little except sugar and glucose.
The easiest way to make them is by traditional methods and I made a few batches of these to get them just right and write a recipe.

The sugarpaste / rolling icing is the stuff you can buy in premade blocks in the supermarkets, suitable for rolling out to cover cakes.... same as they have used to make every factory produced sugar mouse

200g sugarpaste / rolling type fondant icing
tiny little bit of water
flavouring extract
food colouring
cotton string - for tails !

Cut the string to make tails - about 3" long. Put a tail into each cell. This needs done now, as the mixture starts to set the second you pour it and the tails would not stick hen I tried to place them on top immediately after pouring.

Chop up 200g and place in a small saucepan. Add a tablespoon of water (be aware you may need to add a little more), a tiny bit of food colouring and a capful of flavouring extract. We used mint, orange and strawberry (made 3 batches). Turn on the heat and bring up to just below boiling point, until the icing is melted and thick, but pourable. You may need to add a little more water. The icing will crust in the pan and start setting even on the heat. Give it a good stir and pour into each cell.

On pouring each one, Pull the cotton tail (covered in sugar mix) back out and pop it on the top (to become the base)

Leave the mice to harden for approx 30mins until cool and then they'll practically fall out the mould. The mould needs no preparation for sugar or chocolate mice - but will require greasing and flouring if you want to make little mice cakes.

Leave to harden for a couple of days before using food colouring pens (or a brush) to put on the eyes and noses. I did mine straight away, and the colour bled a little as the mice hadn't matured. Saying that - they didn't last long enough to mature !