We can now start production. The cap, the body, the tail, the ink cartridge, and the ballpoint are produced separately and we check the quality of each component before assembly. Next we check that the cap and tail fit on the body and the ink cartridge fits inside. When everything is put together, we ensure that it writes properly and doesn't leak.
In the future, we plan to supply different colors of ink and will re-run these tests for each new colored pen.