Used by some professional shops (Flylogic claims to use it as well as wet etching).

• Procedure * Apply very fine abrasive (optical polishing compound, <100nm grit is ideal) to turntable of some sort * Gently press die against turntable, checking periodically if layer is fully removed *Advantages
• Safe
• Very flat surface
• Moderate cost
• Disadvantages * Requires precision abrasives which may be expensive * Labor intensive ====== Sanding ====== *Procedure
• Secure (glue) die to surface
• Use fine sandpaper (1200+?) to remove a layer
• Using polishing paste, Dremel polish layer to photographic quality
• Advantages * Materials readily available * Safe (for user) * Low cost *Disadvantages
• May not be as repeatable as chemical etching
• Labor intensive
• Risky, easy to grind too far
• Notes**
• Nohl used Dremel + sandpaper for his MiFare Classic attacks according to CCC talk