The invention describes powders for use in the production of spatial structures, i.e. molded bodies, using layer build-up methods, as well as methods for their efficient production. The powders have the special feature that they have good flow behavior, for one thing, and at the same time, have such a composition that the molded body that can be produced with the powder, using rapid prototyping, has significantly improved mechanical and/or thermal properties. According to a particularly advantageous embodiment, the powder has a first component that is present in the form of essentially spherical powder particles, which is formed by a matrix material, and at least one further component in the form of stiffening and/or reinforcing fibers, which are preferably embedded in the matrix material.

A vertical and horizontal mills and discs therefor for grinding particles to submicron size. The mills include two overlapping vertical barrels. Each barrel has a shaft and a plurality of circular discs attached to the shaft disposed in each barrel for grinding materials to submicron size. The discs have an open mesh design provided by overlapping rectangular blades. Each blade has at least two opposing walls orthogonal to a plane defined by the disc. Each disc on one shaft overlaps a disc on the other shaft by from 30 to 45% of the diameter of the discs. An inlet is provided for feeding material to be ground by the mill to the overlapped portion of the discs. An outlet is disposed at an end of the mill opposite the inlet for removing ground material from the mill.