A process for manufacturing a three-dimensional object from a powder by selective sintering the powder using electromagnetic radiation. The powder comprises recycled PAEK. In one embodiment, the powder comprises recycled PEKK. In one embodiment, the powder comprises first recycle PEKK and second recycle PEKK. In one embodiment, the powder consists essentially of recycled PEKK. The process may include the step of maintaining a bed of a selective laser sintering machine at approximately 300 degrees Celsius and applying a layer of the powder to the bed. The average in-plane tensile strength of the three-dimensional object is greater than that of a three-dimension object manufactured by selective sintering using a powder comprising an unused PEKK powder.