There is a neat bag you can buy online that is perfect for storing Legos...it opens up to a large circular play area, and when you are done playing, you pull up the encased drawstring around the outer edge, and it pulls the cloth up and into a bag....capturing all the little billions of Legos inside it 's purse!
When saw the one online, Mom and I began discussing the best, and least expensive ideas...
We decided to use fleece, cut small slits at intervals in a few inches from the outside edge, and ran a small rope in and out around through the cuts. When you do this make sure you have your material spread out, and make it right about that same size...then when you pull up the bag using 2 string parts opposite each other, it will pull up into a purse of sorts.
My grandson, and his friend too, love playing Legos this way....no fuss, no muss....easy open, easy to travel with...and no clean up!
If you have any Lego lovers around...give it a try!