HP USI Stylus magnetizes perfectly to the Lenovo Duet! : r/chromeos
Lenovo USI Pen | Lenovo Nederland
Penoval USI 2.0 Stylus Pen for Chromebook, 4096 Pressure, Magnetic, for Google Pixel Tablet, Amazon Fire Max 11, Lenovo Chromebook Duet, HP Chromebook X360 14b Spare Tips Included : Amazon.nl: Elektronica
Another mod for Lenovo Duet w/USI pen storage : r/chromeos
Lenovo USI Pen 2 for Duet 3 Chromebook is available to order