What is the best way to: How do I prepare a laser printer toner cartridge for refilling it the easy way?
You'll want to melt a hole in the top of the cartridge so that you can pour toner into the hopper. Don't use a drill to make the hole, because it creates too many plastic bits. Use something hot, such as a soldering iron, and make sure no plastic falls into the cartridge. Remove it if it does.