Hanging Gardens is mostly an unusual type of card game in which cards are placed so that they overlap each other and markers are used to claim connected sets of same-color images on the cards. This is simply a replacement marker for the game; the replacement is the third one from the left in the photo -- a little lighter in color because that's how the red filament is.
Small, easy, print in PLA. Either use PLA of the desired color or paint the resulting part.
This part was designed by measuring one of the surviving pieces and constructing the model using OpenSCAD. Quick & easy.