inorganic chemistry - Alloys for inkless metal pen - Chemistry Stack Exchange
Amazon.com : 4 Pcs Metal Inkless Pen Set Eternal Pencil Everlasting Pencil Sustainable and Tree Friendly Pencil Infinite Write Erasable Pens Color Close to HB Pencil School Supplies (Black, White) : Office Products
Amazon.com : Zonon 4 Pieces Metal Inkless Pen Aluminium Everlasting Pencil Metallic Erasable Signing Pen Eternal Pencil for Kids and Adults, Home Office School Supplies (Black) : Office Products