On a Replicator 2 use Raft, 0.20mm (standard) resolution, 4 shells and 50% infill to ensure adequate strength when the rubber band is tensioned. Once printed and the raft is removed you should be shooting within a matter of a couple of minutes.
Use a standard household rubber band approx. 37mm in diameter x 2.0mm wide x 1.0mm thick.
Install the rubber band by holding the rubber band to make a loop. Pushing the looped part of the rubber band through the hole in one end of the bow. Hook the loop over the retaining lug on the bow.
Run the rubber band around the front of the bow (doing it this way around has the least tension on the rubber band so it is easier to install). Push both sides of the unattached end of the rubber band (i.e. making a loop) through the second hole in the bow at the other end and hook onto the lug.
Pull both strands of the rubber band over each end to position it at the back of the bow. Feed the arrow through the centre slot in the bow and position both strands of the rubber band in the arrows notch.
Position your fingers comfortably using the inner finger recesses and around the front of the bow so the bow is held securely but also clear of the arrows path out of the body of the bow.
Pull the arrow back with the rubber band in the notch until only the tip of the rubber band is protruding out of the centre of the bow.
Aim and release the arrow...
Note: There is not a lot of clearance between the arrow and the slot through the bow. This is intentional and is to keep the square section arrow straight as its length passes through the bow. However, check there is sufficient clearance for a smooth delivery to ensure reliable shooting and that the arrow travels a reasonable distance. If your arrow and slot prints with insufficient clearance use a small file on the slot in the bow to increase the clearance a small amount. You can also use a fraction of silicone spray for reduced friction... think of this as a performance enhancement.