You can double the volume of ink or paint stored in the pen by removing the reservoir and filling the body. The reservoir provides a double wall of guaranteed protection, which might be what you want, but it does reduce your carrying capacity.
Other nibs you can use
Use other large nibs, such as the Brause Rose and our Sketch nibs as well as other Brause nibs, some Osmiroid nibs, and selected Hunt nibs
Use adaptors, which let you work with popular smaller drawing nibs