After printing out and playing with a few butterfly knife trainers and toys I noticed features I did and didn't like and decided to give printing my own a shot. Features I focused on were minimizing support material, a clean look, practicality as a comb and maintaining rounded features on the handles.

I don't have any professionally made butterfly knives or trainers, and I only know one or two tricks, which I tuned this design for. I'm open to recommendations from experienced flippers on dimensions and balance.

I plan on revisiting and updating this model as I become more familiar with butterfly knives.

Printing Recommendations

Infill: 100%
Printbed Orientation: all parts with largest surface down on build plate
Support Material: none or build plate only
Material: PLA
Layer height: 0.2mm

Postprocessing and Assembly

6x m2x12 socket cap screws
6x m2 hex nuts
2x m3 hex flat head cap screws

remove sacrificial 1 layer hole bridge on bottom handle scales with a chamfer or drill bit.

Adjust tension with the m3 hinge screw such that the handles just fall freely.

Light oil on the hinge parts can improve feel and function.