A crossbow with a scope. The main body and the trigger is print-in-place.  One of the pictures shows how a rubber band makes the trigger functional. Simply snap the arrow retention/scope in place and attach the left/right limbs with short M4 screws and bolts and you have yourself a functional crossbow.

I used the elastic string that came with the broken wooden one that came with the one I bought.  I believe a stretched-out TPU might serve the same purpose. 

I'd print the arrow tips in TPU to avoid injuries/damage to precious stuff.  I also included 5 different arrow patterns.  No support needed for any of the parts.