I have some older breeders that have tumors and such. I can't afford to take feeders to the vet and I don't think giving them to the snakes is a good idea. So time to put on the big girl panties. What is the best way to put an adult mouse down without fancy equipment or a vet degree.
If they are tumors and not abscesses I would feed them off. Tumors are just extra calories.
If not: A CO2 paintball tank, universal tank adapter, a steel braided hose and a thick plastic bag work well-without building a fancy death contraption.