A mate of mine does this on his hobby farm. A 50/50 dry mix of plaster of paris and flour, puts a small pile on a saucer, puts an old upturned plastic bucket on it with a suitable sized mouse door cut in it, and some bricks on top. He puts it under his work bench with stuff around it like short lengths of timber, other work detritus,etc, to prevent his pets and any other animals getting to it, and renews it as required.
