Pen with Ink-Syringe

Start with an ordinary ball-point pen replacement cartridge. Some are skinny and some are fat; we want one of the fat ones.

Put a one-way valve near the tip of the pen. Add a syringe plunger to the back end.

When assembled, the back end of the pen is double-bodied. Inside the inner body are springs that push on the plunger, so it pressurizes the ink somewhat. The ink can't go out the valve, and it can only go out the ball-point during writing. The pressure, of course, allows writing at any angle. The outer body of the back of the pen holds the standard click mechanism, of course.

When the ink runs out, take the cartrige out of the pen and insert point into an inkwell. Pull back on the syringe to refill the cartridge body, with ink flowing through the one-way valve. It is possible that the viscosity of the ink might make this a slow process, so an additional gadget, mounted on the inkwell, could be used to hold the pen cartridge. This gadget would use springs to extricate the plunger.

When done, wipe off the ink on the outside of the point (or just start using a spare cartridge while the first sits in the inkwell gadget), re-assemble the pen, and continue writing.