Weighted Balisong M4 Fasteners

Edit: I've reverse-engineered the model into proper STEP files if you want to edit it. Also available on OnShape under the name Balisong Mk II.

The STEP files are the most up-to-date files and the ones I would recommend using. With PrusaSlicer 2.5, you can now import and use the STEP files directly. 

Print one handle normally and another mirrored. There is both a double ground and single sided blade; the single sided is much easier to print and my recommendation. Fasten together with 2 M4-16mm bolts, 4 M4 washers, and 2 M4 locknuts (you can use normal nuts, but locknuts are recommended). There are spaces in the handles and blade to add M4 nuts for weight.

The balisong is slightly longer overall than the original, which I thought was a bit short. With all 43 M4 nuts added for weight, it is reasonably heavy, although still nowhere near the weight of my metal bali trainer.

Total weight:
70 grams (2.5 oz) with all nuts added.
40 grams (1.5 oz) without any nuts for weight. (100% infill)
For comparison, weight of my metal trainer: 170 grams (6 oz).

You may have to re-orient the STEP files for best printing. There is also a version without any holes for nuts if you just want a quick and easy assembly.

Fasteners required:
2x M4-16mm bolts
2x M4 locknuts
4x M4 washers
43x M4 nuts (for added weight)

With a bit of silicone lubricant, it flips pretty well: https://youtu.be/p450AaAcBeI