We got a new play set from the sad demise of Toy R Us a few weeks ago. When my four year old started throwing toys into the second floor, because she couldn’t climb and hold them, it became clear we needed a winch.
I made a quick design in Inkscape and using 1/4" plywood from Invetables I cut out the spool. Then using spacers, pulleys and bolts I had on hand, I attached it. I used a zip tie as the stop so that it would give if she put to much weight in or a kid caught on the string.

File is attached, but keep in mind I used 1/4" plywood that wasn’t Proof grade so you may need to adjust the boxes within the circles or redraw them. .