An apparatus originally conceived for directly preparing capillaries of powders of reactive alloys for x‐ray study inspired the present device. The unit is simply a hermetically sealed chamber which is provided with a drive mechanism at the top, specimen and sight ports at the sides, and a funnel at the bottom. The drive mechanism is used to rapidly rotate a rotary cutter. Particles of any desired size are produced by a suitable choice of cutter and screen. The unit is extremely effective in its original role but has been used to prepare small quantities of powders of reactive alloys for other purposes, and is a versatile research tool.