Krightlink Foam Roller for Deep Tissue Massage, 13" High Density Exercise Roller for Muscle Massage and Myofascial Trigger Point Release, Back Roller for Fitness, Yoga and Pilates (Blue)

I've also had issues with costochondritis. There are a few specialized stretching devices for it, but I had the best luck with a yoga roller I found at Five Below. I leaned against it in my chair, and rolled back and forth, and it almost immediately made a huge difference in my pain levels. After a few weeks, it was basically gone. You can find yoga rollers cheap, but here's an Amazon listing just for the picture: https://a.co/d/061RUs0a Also, be aware that the costochondritis sub is run by the person who created and sells an expensive stretching device. The sub advice tends to be heavily favored towards that particular device.