Printing with powder allows higher resolution prints, at the expense of 'solidness'
One solution to the problem is to infuse the printed object with an additional binder, commercial printers use a proprietary powder, a binder, stability is achieved by infusing with Cyanoacrylate.
Open3dp.me.washington.edu publishes alternate recipes for 3d printing, including printing with plaster, ceramic, glass and more. Powder Printer Recipes.
Printing a full mendel using this process has it's drawbacks, the picture shows an X Carriage printed using plaster with a CA infusion.
The material comes out quite hard, with the appearance of a concrete block. Like concrete, the material is brittle under stress, but quite solid under normal use. Like acrylic, care should be taken when tightening bolts. One tightened down hard caused a sizeable crack. Because the part is flooded in CA, it is quite easy to fix by adding more.
There is no flex, so it is unsuitable for 100% of the printed parts (printed springs don't really work). We believe that about 80% of the parts can be printed using this process. with the others printed or purchased.
One use of powder printing in mendel bootstrapping is obvious. Print the parts and use them as mold masters. using the process described in Moldmaking Tutorial.