The Rotring Rapidoliner is a technical drawing pen used by illustrators and graphic artists and designers. The Rapidoliner consists of three parts: the outer pen casing, cap and a disposable cartridge unit that runs the length of the pen. The refill cartridge includes an integral nib in a choice of 0.18mm, 0.25mm, 0.35mm, 0.5mm and 0.7mm widths.At the time of publication Rotring has discontinued production of the Rapidoliner and it is very difficult to source replacement cartridges
Find a replacement Rapidoliner cartridge. Rotring no longer manufacture the Rapidoliner or the refill cartridges, and as a result, you are unlikely to find the cartridges or pens in a shop. Check auction websites, classified adverts in trade magazines and school or college publications with a For Sale and Wanted section.
Remove the pen cap and detach the cartridge from the outer dark red casing. The refill cartridge consists of most of the pen, including the nib and top casing where the nib size is stamped on.
Discard the refill cartridge. You should now only have a pen cap and the outer casing remaining.
Slot the refill cartridge inside the outer casing and secure it in place. Replace the pen cap.
If you find a seller, buy in bulk because the refills are extremely rare and there are a lot of designers and illustrators on the same quest as you, tracking down refills for their favourite pens.
Consider using a similar pen if you are unable to find a refill for your Rapidoliner. Rotring's Rapidograph and Isograph are still in production and provide a comparable drawing experience.