A filter bag assembly for a juice press is assembled from a unitary sheet of fabric and at least one coupling member and/or belt. The fabric sheet is foldable along a transverse fold line and then along left and right fold lines to form a seamless bag having left and right side margins each having four sheet layers. A left coupling member may be arranged to gather at least two of the four sheet layers of the left side margin, and a right coupling member may be arranged to gather at least two of the four sheet layers of the right side margin. Each belt connects the left side margin to the right side margin. Preformed holes in the fabric sheet are positioned to allow the coupling members and belt(s) to be installed to retain the folded bag. The assembled bag is inexpensive and the fabric sheet is replaceable.