Most guinea pig costume designs are made from conventional dress fabric materials, but if you want your guinea pig to stand out and stay protected, why not outfit it with handmade scale-mail armor?
Many pet costumes are focused on its aesthetic appeal and not enough on protection. The handmade guinea pig costume armor is made from polished steel scales and steel rings that were woven together, just like the type of costumes you'd see at a medieval LARPing event. The helmet was bought from a Renaissance Faire, which is also included in the set.
The steel-made guinea pig costume is currently up for grabs on eBay with the profits benefiting the Metropolitan Guinea Pig Rescue of Virginia.