We have been happily using a packable bowl for dog food for quite some time. It is sturdy, waterproof, relatively light and very cheap (less then 4 Dollars/Euros at Biltema ) It works better than a rigid plastic bowl, which is harder to pack, especially when my dog carries it in his own small backpack. The only problem is that is can not be closed when soaking freeze dried dog food.
Then I saw this great idea by Ruffwear for a dog bowl with a cinch top. So I modified my own bowl accordingly, simply sewing on an cuff with a drawstring, similarly to a simple stuff sack. Works great, also for carrying kibble during day trips. Weights 85g (3oz).
