Stir plate advice

Im trying to build a stir plate for the first time. I have some 3.5" computer fans but they dont spin very fast.. i have magnets out of some old hard drives.

The container that i am trying to use is a 2000 mL storage kimble. its a very nice bottle the only downfall is that the bottom is convexed.. So the 1" lab stir bar i have wont stay on top of the hump and spin it just sits on the side.. how could i get this to work?

The convex bottom is not gonna work. It needs to be as flat as possible. Its okay of your fan spins slow and the hard drive magnets are very popular

Strong magnets can also interfere with the motor itself - I've got my magnets suspended above the motor windings on a ring of aluminum (non-magnetic). I also had a Kimble Konte flask, it had a nice cork wrap near the neck, awesome - but the bottom wasn't flat enough. My Pyrex flask works fine.

Gonna need to get another vessel for your starters. I spent the money on an Erlenmeyer flask and love it but there are other routes to go if need be.