Novices and newbies discussion

My Dom has asked me to locate a suitable chastity cage for a beginner. I need something affordable yet decent in quality, and it must come in a smaller size—specifically with a tube length around 4-5cm and a ring circumference of approximately 40-45cm. Sir thinks we are most likely looking at plastic, but an inexpensive metal option is acceptable too, provided there’s no chrome involved (referring to the material, not your web browser). Thank you for any recommendations or guidance:)