Among other things, a case forming system is provided. The system includes a conveyance apparatus for conveying case precursors along a conveyance path and a case set-up apparatus characterized by a case forming member. Upstream case precursors are conveyed along the conveyance path for operation thereupon by the case forming member. A case forming mandrel of a mandrel assembly is movably mounted in relation to the conveyance apparatus for continuous motion with respect thereto. The continuous motion is delimited by travel of the case forming mandrel between an upstream locus and a downstream locus of the conveyance path, and reversible extension of the case forming mandrel towards case precursors during travel between the upstream locus and the downstream locus of the conveyance path.