My son wanted a trainer balisong (aka butterfly knife) for his Halloween costume. I found a few 3D Printable designs out there and printed them. But the weight and size never seemed right. So, I figured I would just custom design one for him. 

Print Settings: I printed the first few layers with an accent color, no bottom layers, and 30% honeycomb infill. Then I did a M600 color change and switched to 100% rectilinear infill for weight.

The only hardware required is Qty:4 M3x10mm button heads, and Qty:4 M3 hex nuts. If you want more weight you can swap the printed pins for 5mm OD metal pins (qty:6 x 10mm, qty:2 x 12mm). 

I have included the plate of STL's as well as a STEP, the original Solidworks files (sorry can't upload the assembly… printables still doesn't support the .sldasm file type). I also included a link to an Onshape import.

Onshape: https://cad.onshape.com/documents/e653a823015d37890a0a78f6/w/8b21972e8d6b2f68293fe0e7/e/1a2cb4fab845d202c35e7a39?renderMode=0&uiState=633b02c5179c912951c45efd

Video of my feeble attempt at a balisong flourish: https://photos.app.goo.gl/tg8wC2idECXPQcQW6

Modify and customize it to your hearts content.

Update: Added a rounded tip version of the blade as an optional download (More Kid Friendly)