
Id also recommend you dont use sawdust.. i use bob martins paper cat litter (make sure its paper and not 'paper based')or Animal Dreams mini compressed cardboard. I know other people use a product called Carefresh.
Sawdust contains tiny dust particles which badly affect small rodents respiritory systems, and also the phenols in the softwoods used will do damage (both of these are reasons people working closely with sawdust wear nose/mouth masks!!!).
I have always used small empty cardboard boxes for small rodents, mice, hammies and rats all love them. (the boxes that contain ten packs of AMP/Prizechoice frozen meat are superb for rats!)
I also collect newspaper from a local newsagent and shred it at home with an office shredder to make safe cheap 'nestly' bedding.