Rohloff Lock-Ring Tool (for 8540L/8540SL) Gates Carbon Drive Sprocket 
Survives the 30 Nm tightening torque with a torque wrench and 27 mm socket wrench

M3 x 30 mm Hexagon socket countersunk head screws ISO 10642 / DIN 7991 
M3 hexagon nuts self-locking (with polyamide clamping part) similar to ISO 10511 / DIN 985

Screws from above (side with 27 mm socket wrench) and secure with hexagon nuts from below, four screws are sufficient for secure tightening of the lock ring.

Suppport material is not needed.
Printed with Fillamentum PLA with slightly higher temperature.