According to some embodiments, a holding device for a detonation initiation system is disclosed. The holding device includes an initiator holder having a longitudinal internal cavity. The longitudinal internal cavity is configured to retain an initiator and an electrical cable in electrical contact with the initiator. The holding device further includes a plurality of retention fingers configured for retaining a shaped charge adjacent the initiator. The plurality of retention fingers define a shaped charge receiving portion that may be configured to receive shaped charges of different shapes. The holder may be formed from a thermoplastic material.