Lasko 20 Inch Box Fan Replacement FanHub and Fanblade

Our Lasko fan fell down and one blade snapped and hit the other blade, so it became unusable.

Since the motor is still good, I figure we could just print something to replace it.
As printing the whole Fanblade would be too large and also PLA is not really good for fanblade, I figured that I can design a hub that can slot cardboard as fanblade.
I experimented several shape of fanblade, but at last since I had access to a LASER cutter, I drew a pattern so that the cardboard can double the layer so that not to be too flimsy. The cardboard I used is just cereal box, I have attached f3d archive source file, so if you want to use thicker cardboard, you can increase the gap of the slot.

Included in the files
The fan hub f3d and stl (The rings on the bottom of the fan hub is so that it seems to help with warping problem, you can totally remove it if you don't like it, the design has 12 slots, so you can experiment with 2, 3, 4, 6, 12 blades that's mostly balanced since it's running at very low speed)
The schematics of the lasercut for cardboard, doubled up in thickness (in Illustrator, blue is engraving cut for a guided fold, red is cut through, you can also just use scissors/cutters to make your own blades, have the source DXF file also, if you need it, DXF is not colored so you'll need to adjust before LASER cut)
Some photos of failure (warped print) and final assembly.