WHAT'S IN THE BAG!!!!!
Satchels
Gathering Satchels increase your storage capacity.
Each level should/will have an appropriate bag and MUCH more for each Artisan Profession.
Material Tab
Add them to your bag slots.
Remember you drop a portion of materials in this tab upon dying, players can also choose to loot your materials with risk (flagging). Be sure to find a management system for storing that works for you!