[bhumudar]

Adding to slijjin's comment, you may also want to make sure that the pulleys that you use have a flange on them so that the belt doesn't fly off. Also you could make a set of lexan washer instead of pulleys with flanges. As for as attaching the pulleys, boring out a hole with a lathe (if available, if not a mill will work just fine.) and broaching the key slot.

P.S. McMaster sells rods with key slots already in them.