this is a remix from the thingiverse : https://www.thingiverse.com/thing:4393969
You can print just the top and add it on the original print or print both part. I had to print it at 103% because of the decal stickers on the legs. use screws to attach the 2 pieces together.
The leg attachments can slide up and down the leg determining the height of the footrest. The inner hole for the leg is made of 2 compound angles, because the legs of the chair are angled forward and to the side. This allows for the footrest plank to be parallel to the ground and to be comfortable.
The author remixed this model.