I've been using an older Z-corp powder-bed printer, and the last word I'd use to describe the print-heads is "robust" - they will clog on anything thicker than distilled water, and sometimes have trouble with that. I think you'll experience the same difficulties with any printer that depends on an ink-jet printhead. Also, as you seem to have discovered, the manufacturers of these machines don't think of their machines as an open platform which users are encouraged to experiment with. A big part of their business model (taken from the same playbook as 2D inkjet printers) involves selling the consumables at high prices.

I'd suggest you develop a machine of your own, perhaps building on an existing one so you don't have to reinvent the powder-spreading mechanism. Instead of using an inkjet printhead, substitute something with much larger orifices, like an airbrush, that won't have any problem handling thicker binder solutions. Since the patents on this type of machine seem to have expired, there are relatively inexpensive versions available, like the "3D Pandora" that you can experiment with.

Andrew Werby
www.computersculpture.com