This is a crossbow toy using the trigger assembly posted previously. 

The geometry of the trigger of this toy is 75% of the size of the full sized version.

Here it is in action:

The trigger should reset by pushing the trigger backwards. The geometry of the assembly has been refined a little bit from previous versions so it should reset more consistently.

The prod is intended to be mounted using a string. I wanted to keep the aesthetics of this since that's how the prods were traditionally mounted, and there are plenty of other print-in-place crossbow models already. If you don't want to do that then you'll have to glue it, as it wouldn't friction fit on its own. If you don't mount the prods, you can still use the toy to shoot rubber-bands.

The model is roughly modeled on Han style crossbows. They are categorized by their long draw length using full sized bows as prods, mounted without a stirrup. The handle is said to be relatively tiny, only allowing three fingers or so to fit through.  

To load the crossbow, a crossbowman would sit on the ground, and place both feet on either side of the prods and pull: