The CraftBot is an excellent piece of hardware. One of the few weak points in the design is the stiff yet flimsy little nylon nut used to hold the build plate in place. I lost a large print once when the vibrations made the nuts come loose, and the plate actually fell out of the machine during the print. This modification consists of a knob printed in flex material, with a metal M4 nut inside. It holds the plate with a firmer grip. Print a pair of these with your favourite flexible filament and stick a M4 nut in each. Note: The printed things on my pictures are an earlier revision of this thing, so they differ a bit in height compared with the STL file.