a container/box to put stuff safely away or out of sight. The Ultimate Version is Designed to fit Stabilo fineliners Perfectly. It's an exact fit. If your printer is calibrated properly this should give no problems. If you think it's going to lock. Try rubbing it in with a drop of olive oil to reduce the friction of the material. (or if you can controle the flowrate for the outer layes, reducing it to 85 to 90%). It's Like 2 people who are both perfect as individuals. But still need to smooth some of the edges to really make it work.