Best make a rock polisher
NATIONAL GEOGRAPHIC Professional Rock Tumbler Kit- Advanced features include Shutoff Timer and Speed Control - 2lb Barrel, 1lb Gemstones, 4 Polishing Grits, Jewelry Fastenings and Learning GuideNATIONAL GEOGRAPHIC Hobby Rock Tumbler Kit - Includes Rough Gemstones, 4 Polishing Grits, Jewelry Fastenings & Detailed ...