FPS stands for "finger pointing slingshot" ... and that is to be taken literally, because the hand position with this sling is actually like that.
The holding power of the hand is reduced to a minimum. The slingshot rests between thumb and index finger. Due to the narrow handle in this area with the pronounced rounding, the fork aligns with slight pretension of the bands almost by itself.
The little finger fixes the grip and the ring finger and middle finger only prevent the shot from falling out of the hand after the shot.
The back of the hand and forearm are aligned almost in one line, which further reduces the risk of blurring.
Some shooting action in the woods and also near a lake:
The fork width is 100 mm (outer edges).
In the data-sets I have provided a massive version as well as a skeleton version. Both for right and left-handers.
Have fun with it.
Pay attention to your safety and those of others.
5 lines for wall
13 solid top and bottom layer
You will need support to print the slots!