Some tines I fnd that lining a peice can be quicker than using a facing or a binding. Lining the short sleeve of the 2 + 2 tunic is pretty easy. Just cut an extra sleeve set from another fabric - which could be a lighter weight or a contrast fabric, etc. It sews up clean and neat. You could even insert piping or ric rack for a cute edege treatment. Using ric rack in between the sleeve and lining gives a saw tooth effect. I don't usually use a lot of piping (or ric rack) but it would look cute around the sleeves, the patch on the front and at the neck line next to the binding/ties.