The method we use involves having two cages side-by-side or a smaller cage within a larger cage. Some will even split a cage down the middle using wire, this is called the split-cage method. For all these methods, each chin would either be in opposite sides or one would be in the smaller cage while the other is in the larger cage. Each animal would have access to their own food, water, hay, and cage accessories. Everyday, each chinchilla should be put in the others cage or side (at this point, the chinchillas should never be in the same side or cage together!) to get used to the new smells. This would mean that every day each chin will reside in the opposite cage that they were in the previous day. The chinchillas will need to live together in this way for at least 2 weeks before allowing them to freely roam together within a shared cage.
If the chinchillas still fight or act aggressively towards one another, more time may be needed for them to become comfortable with one another. These methods can be used indefinitely to attempt to get the chinchillas to bond. The key is to make sure that they can always see and smell each other. This way, they will always know the other one is there and will not forget their scent.
Worst case scenario, you may need to be prepared to have another cage on hand if the chinchillas never bond. There are some chinchillas that do enjoy living alone, it is not uncommon for older established animals to not accept a younger cagemate. Although we hope for the best, it is always a good idea to also be prepared if it doesn't work out.
Many times we get asked this question. Allowing chinchillas to briefly meet prior to adoption does not indicate whether they will get along or not. Many times we have had owners bring their chinchilla and put the newly adopted chin in with the other. Usually, the chinchillas will act fine upon first observation. But as soon as they are home, fighting ensues. Due to the stress of a car ride, the unknown environment and a new friend to meet, most chinchillas will be overwhelmed to the point that they will not act the way they would normally in their familiar home habitat.
This is why we don't encourage you to bring your already established chin on adoption day. It can cause unnecessary stress on both animals and usually does more harm than good. The best way to ensure they bond and get along is following the side-by-side or cage within a cage method. This way they can get used to each others smells and slowly integrate over a few weeks. This reduces both stress and aggression which will prevent fights breaking out and unnecessary tension.