Invisible Sticky Sand Prank Ball

I’m planning a harmless prank for my YouTube channel and need a small, sand-coloured ball that practically disappears against a typical road or footpath until it’s stepped on or picked up. The core requirements are simple but specific:

• Composition: use only natural materials for the ball itself.
• Activation: when I add a few drops of organic water type liquid, the surface should turn tacky enough to cling to a shoe or hand, yet lose that stickiness on its own after roughly three hours.
• Colour: I want the freedom to tweak shades so the ball can match different outdoor surfaces (brown, grey, beige or any close custom mix I request).

Your deliverable can be either a ready-to-ship prototype or a clear, repeatable recipe with step-by-step instructions and sourcing details for every ingredient. The ball must be safe, non-toxic, and leave no lasting residue once the three-hour window passes. If you’ve worked with eco-friendly binders, clays, or sand composites before, that experience will be invaluable. Let me know how you would approach testing durability, stickiness duration, and colour matching, and we’ll move ahead from there.