Here's some awesome art work our whole family made today using my son's Lego Mindstorms to build a super high speed turntable. Instructions for that are here: http://www.nxtprograms.com/spin_art/index.html
We then used paint and markers to create our works of art. Once we had our artwork done, we selected several we liked and used mod podge to attach them to a stretched canvas frame.
NOTE: You may want to place the turntable into a large bowl with high sides to prevent splattering paint all over you and everything else.