There are several potential benefits to using glass and metal dildos:

1. Hygienic: As non-porous materials, glass and metal dildos are easy to clean and sanitize. They do not absorb bodily fluids or bacteria, making them a good option for people concerned about hygiene.
2. Temperature play: Glass and metal are excellent temperature conductors, which means they can be easily heated or cooled for temperature play. This can create a unique and stimulating sensation and be useful for people who experience pain or discomfort during intercourse.
3. Texture: Glass and metal dildos are known for their smooth and firm texture, which can provide a different sensation than softer materials like silicone or rubber. Some people find this texture more stimulating or enjoyable.
4. Durability: Glass and metal dildos are generally durable and can last long with proper care and storage. This can make them a good investment for people who use sex toys regularly.
5. Aesthetics: Glass dildos, in particular, can be quite beautiful and artistic. They are often hand-blown and come in various colors and shapes, making them an attractive addition to a sex toy collection.

It's important to note that every person's experience with sex toys is different, and what feels good for one person may not feel good for another. Therefore, as with any sex toy, it's important to choose a material and style that feels comfortable and enjoyable for you and to use the toy safely.