To mark what flavor was in a cart/carto I tried little colored rubber bands first but my PCC would move them or catch on them and eventually pull them off when I removed a cart.
I saw these 1/8 inch map dots and ordered them to see how they work out:
Amazon.com: Map Dot Stickers - Assorted Colors (Transparent - 1/8" Diameter: Office Products
I saw these 1/8 inch map dots and ordered them to see how they work out:
Amazon.com: Map Dot Stickers - Assorted Colors (Transparent - 1/8" Diameter: Office Products