This Material Pack contains 37 different Wall Materials. It also includes 23 different Material Instances. Easily Create your own instances using the Masters. I may update it to include 37, or more, instances, but I really didn't see it necessary because of similarities in the materials. Plenty of variety was already possible.

Cobra Metals Materials Pack

https://www.unrealengine.com/marketplace/en-US/product/68b1d7d07ad242b0bcd7dadc4448a749

Cobra Concrete Materials Pack

https://www.unrealengine.com/marketplace/en-US/product/c1f6d274aa934d7e838f59d558de60d8

Cobra Fabrics Materials Pack

https://www.unrealengine.com/marketplace/en-US/product/681e1f0334f1487996d53043274ab825

Cobra Rocks Materials Pack

https://www.unrealengine.com/marketplace/en-US/product/679da06f0c1d487d90f79f90c0c856d6

Cobra SciFi Materials Pack

https://www.unrealengine.com/marketplace/en-US/product/c5fd82c35bea4194894bcb80f966d990

Cobra Floors Materials Pack

https://www.unrealengine.com/marketplace/en-US/product/5da6e2b8da8547d8bb78c4123252f729

Cobra Synthetic Materials Pack

https://www.unrealengine.com/marketplace/en-US/product/5da6e2b8da8547d8bb78c4123252f729

Cobra Wall Materials Pack

https://www.unrealengine.com/marketplace/en-US/product/70072b4abcdc47ef977db4f0d9d5ae89