Define core as prelam to lock finished thickness

Fix a finished panel thickness by defining the core material as a prelam board so laminates cannot be changed later.

1. To fix a finished panel thickness so laminates cannot be changed later, define the core material as a prelam board in the admin portal.

   ✓ 已于 2026年10月16日 在产品中核实

2. Once the core is set as prelam, the laminates are locked to it and cannot be altered.

   ✓ 已于 2026年10月16日 在产品中核实