trial product; prototype
Refers to a product made on a trial basis, often for testing or demonstration before mass production.
This prototype still has room for improvement.
We plan to unveil a new trial product at next month's exhibition.
試作品 refers to a trial product made to test manufacturing or function, while モックアップ is usually a static model for visual or ergonomic evaluation.
Compound of 試作 (trial manufacture) + 品 (product, article).