Here is a couple of pics from the 3d model i've been working on. I was planning on getting the blades laser cut out of 1.2mm thk mild steel and folding out the three fins on each blade. The fins act as spacers between each blade as well as generating the wind effect to clear debris. I also went with a slotted hole to mount on shaft to be able to replace individual blades if damaged without having to remove the assembly. I was going to weld each blade to the next on the fold out flaps, and weld every 5th or 6th blade to the shaft. not huge amounts of welds, just tacks.