[Nullset] uses inkjet printer technology for his 3D printing needs. We usually think of hot-plastic printing like the RepRap or Makerbot when we hear about rapid prototyping, but this setup uses a liquid bonding agent to turn powder into a solid structure. Standard inkjet cartridges can be used to precisely place the bonding agent, but it’s hard on the heads and you have to replace them often. [Nullset] is getting pretty good at it, and decided to write a tutorial on the modifications necessary to print with bonding liquid.
At its core, the method injects binder into the cartridge through one port while using a second for drainage. [Nullset] found that the needle fittings used to inflate a basketball work great for this. He drills a couple of holes that the threaded end of the needles fit into. That connection is sealed with some epoxy, and the tubing that delivers the binder is zip-tied to the needles. A bit of purging is necessary to get rid of any old ink, but after the initial flush you’ll be up and running pretty quickly. He figures the whole process can be one in around 10 minutes once you get the hang of it.