Paint mixing attachments are huge time savers, but they can also make a mess of things. Drill a hole through your paint lid, then work the top of the attachment through the hole and secure the lid before mixing to ensure the paint remains in the can and not on your floor.
Start by using a ⅜" bit and drill a hole directly through the centre of the lid of your paint can or bucket. Remove the bit slowly and clean excess paint from it.
Then, remove the lid and slide the mixing attachment through the bottom of the lid before re-attaching the lid. Use a rubber mallet to make sure the lid is securely attached. Attach the drill and start mixing. You can see a full video of the process at the link below.
Tip for Mixing Paint with a Drill Attachment [Today's Homeowner]