Link to Video
https://youtu.be/d_w8NJa38pg

This Slug-Throwing Slingshot has a low friction rail to increase accuracy. While it may appear like a crossbow due to the trigger and crossbeam, it does not store its energy in the crossbeam, and stores it in a rubber band instead, thereby functioning as a slingshot.

It is made from 3D Printed PETG components, wooden stir sticks from Home Depot and Lowe's, small rubber bands, glue, a nail, and a single exercise band. The slug it shoots (striker/firing piece) is a 10g piece of PETG that locks with the trigger. The power can be adjusted by increasing the distance between the crossbeams and the trigger or replacing the exercise band with a stronger one. I find the weaker ones are sufficient, as the stronger ones provide minimal improvement (they rub against the rail more, reducing the exit velocity).

The rails are V-shaped, which causes the cylindrical striker to sit nicely in the center of the rails as it accelerates forward, making for very consistent performance when combined with the minimal surface area contact between the two pieces. The rails are printed horizontally on the print bed at a high print bed temperature to prevent warping (the smallest amount of warping will reduce performance). This also ensures the layer lines are parallel to the direction of travel, causing the friction to be greatly reduced. The angle at which parts are printed is critical to maintain high strength in the direction the forces act. The firing piece/striker is printed at a diagonal so maximum strength along the weak spot where it has a groove.

The length of the rail is very much dependent on the exercise band being used. The one I constructed has 2 rail sections following the initial rail section with a trigger groove.

The parts were printed on an Ender 3 V2 in PETG. Use the biggest nozzle size you can get away with.