I've used an actual lava lamp, gutted it and at the bottom i mounted a DTR fan with two 3mm(I think) square magnets, and two at the bottom of the lava lamp. To create a simpler tornado like effect.
Just thought some might want to know:
C6 DIY Cree LED Flashlight Full Casing/Shell with Driver Pill (2*CR123A/1*18650) - DX Offers - Free Shipping - DealExtreme