https://www.thingiverse.com/thing:51489 \Pull String Helicopter by 271828 February 17, 2013

Mine is a remix of this. Also, thanks to some of the propeller people, and https://www.thingiverse.com/thing:2498641 , the beveled plate

and reinforced shaft https://www.thingiverse.com/thing:2964180

this is still a work in progress, but this saves print time

I redesigned the handle/shaft, I cropped it to use just the top, and removed the handle part. I REPLACED the handle with 3 / 4 inch PVC, 3 1 / 2 inches long, and took dremel drill and cut out space to access the rubber band, and left it intact at the top.

I created a CONNECTING WASHER, flat part gets glued to the top of the prior handle, and bottom part centers on the PVC, again using glue

I USED GORILLA GLUE, see picture

I then used 3 / 8 inch PEX (could use PVC also, even 1 / 2 inch PVC), 3 1/2 inches long, for the pull handle, to attach string.

See photo, see all parts.

Then see it assembled, top part, glued to washer, glued to PVC pipe, and camshaft/connector inserted.

The small plate for ruber band, and the pull handle, are not attached to string or rubber band yet.

I used 3 inch 1 / 4 rubber band.

AND, I used fluorescent #18 nylon, got it at Lowes, it is thin, strong, and it actually REWINDS THE STRING !! first, need to add a couple twists to the rubber band

AGAIN, a work in progress, but saves printing time !