Summary

These files were designed using fusion 360, I made this just for fun and to learn a bit of 3D modeling too. The lenght of the base is approximately 7cm or 2.75 inches.
You will need CA glue and a toothpick for this to work.

Print Settings

Printer:

RepRap with Marlin

                                            <p class="detail-setting rafts"><strong>Rafts: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting supports"><strong>Supports: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting resolution"><strong>Resolution: </strong>                     <div><p>.2mm (doesn't matter)</p></div></p>                                                                                <p class="detail-setting infill"><strong>Infill: </strong>                     <div><p>10%</p></div></p>                                                        <br>                        <p class="detail-setting notes"><strong>Notes: </strong>                    </p><div><p>You can print the support for the trigger separately, so as to have a stronger part because of the orientation of the layers, you can also print the base with no supports for the trigger and use it as a normal catapult.<br>Everything was printed using white ABS.</p></div>

Post-Printing

You need to insert a toothpick in the support for the trigger with the trigger in for it to work.
And maybe you'll need to use a craft knife and clean the hole in the base for the arm to fit in. I glued mine in place with CA glue.

Mini Catapult with trigger