I think I came up with the pattern of bag I want to make:

I am concern though from how it should be closed. I tried to put a long piece of Velcro (from one side to the other), but it doesn't feel right: the Velcro is really strong, and it feels like a struggle to open it. Maybe I should divide this 12'' long piece into 2 smaller pieces. Another thought I had about it is to locate the Velcro lower in the bag - right below the circle. That way it would be more interesting plus it would be easier to open the bag.

I don't want to use felt in this bag just because it feels not balances - weight wise. The felt works good in the small purses, but when it is bigger bag I don't like it...

I also think I will use only one layer of Tyvek and not two. I wasn't sure what I like more so I decided to choose the one that costs less time to build... That also means I will actually have to buy Tyvek - I need blank Tyvek and the one I used so far has prints all over it.