A closed loop recycling process of manufacturing a foam part includes dispersing a filler material recycled from an additive manufacturing (AM) process in at least one foam reactant and pouring or injecting the at least one foam reactant with the filler material into a mold and forming the foam part. The foam part has a foam matrix with between 2.5 wt. % and 30 wt. % of the filler material. The filler material can be a recycled powder from a selective laser sintering process that is not graded (i.e., sized) before being dispersed in the at least one foam reactant. For example, the recycled powder can be a recycled polyamide 12 (rPA12) powder with an average particle diameter of less than 100 micrometers. Also, the least one foam reactant can be a polyol reactant and an isocyanate reactant such that a polyurethane foam matrix with recycled rPA12 filler material is formed.