Here is how I make them. I make inkjet decals of them to apply to a clear plastic disk.
To make the decal, I scan the kit prop in my scanner. My photo editing program has blur functions- a linear and a rotary blur. I choose the rotary blur using the hub as the center point and set the blur at about ten degrees. Then I add a second layer, with a colored circle of the diameter I want the prop to be. Then I add a third layer, which will be the final decal. I then copy the blurred prop, set the transparency to about 25-20 percent and paste the prop image into that third layer. Now I delete the first and second layers, and print out the resulting image onto decal paper. I cut out the decal and apply it to the plastic disk. Makes a great blurred prop. I then slice the hub and the blade plane and glue to front of disk.