You can now Craft special (one use) items with materials you can find in the levels (you find one per 2 level finishes) There is a total of 12 different items, currently there are 2 recipe's you can craft, if your interested in them, you can see them ingame (Main menu > Inventory button top right, click Craft & Inventory, and there you can see the recipe buttons on top, click the learn more button top left for more information)
More crafting recipe's are coming soon.
Players can sell items, the server will automatically pay and tax the player when selling an item, then the server will list the item and sell it to another player in the Marketplace, make sure you check the marketplace often, because prices might swing : )