Selective laser sintering (SLS) is an additive manufactur- ing (AM) process that builds 3-dimensional (3D) parts by scan- ning a laser beam over powder materials in a layerwise fashion. Due to its capability of processing a broad range of materials, the rapidly developing SLS has attracted wide research attention. The increasing demands on part quality and repeatability are urg- ing the applications of customized controls in SLS. In this work, a Youla-Kucera parameterization based forward-model selective disturbance observer (FMSDOB) is proposed for flexible servo control with application to SLS. The proposed method employs the advantages of a conventional disturbance observer but avoids the need of an explicit inversion of the plant, which is not al- ways feasible in practice. Advanced filter designs are proposed to control the waterbed effect. In addition, parameter adaptation algorithm is constructed to identify the disturbance frequencies online. Simulation and experimentation are conducted on a galvo scanner in SLS system.