There are two technologies I know of for injection molding hollow parts: One is
Die Slide molding from JSW; the other is a new Engel technique called joinmelt.
And don't miss the unusual or first-time demonstrations of special techniques like melt oscillation (Scorim process), hollow-parts molding (
Die Slide process), gas counterpressure, gas assist paired with LIM or multi-material molding, and new water injection molding (it's like gas assist without gas).
The undercuts (if any) are then used to guide the construction of
die slides. The resulting cover and ejector die models also can be treated as die cavity inserts, and die bases can be constructed by user input, important die configuration factors (undercut, parting line, projected area, etc.) are automatically calculated and can be used to evaluate different die configuration plans.