This is a balisong trainer I've been working on for a while. I've designed all the parts myself. I've kind of hit a wall on the design, however. That's why I'm uploading it here. Hopefully enough people will work on it and we can get a trainer that works great. I'll add exact sizing of parts soon.
I use sexed barrel bolts for the pivots, stainless steel washers, metal zen pins from american knife maker, and #10 mechanical bolts and nuts for the spacers. I glue the scales to the handles.
Overall, the knife is a little light. I'm still brainstorming a reasonable way to add weight. It flips well but the tolerances need tweaking.
2 - 3/4" x 1/2" barrel sex bolts for pivots
4 - washers that fit between the handles and the pivots
2 - Handle 1
2 - Handle 2
2 - Scale 1
2 - Scale 2
2 - Zen Pins - you can use whatever works best for you. I've used carbon fiber rods before
1 - Set of Spacers
4 - # 10 Bolts w/ nuts
12 - #10 nuts for weight. You can use whatever fits.
I usually print at 0.2mm layer height on everything and 75% infill for weight. You'll notice that there are slots on the inside of the scales and outside of the handles. I glue #10 nuts in there for weight. You can use anything that fits.
The biggest issues will be tolerances between parts. I've had to drill out the holes on the blade for pivots from time to time.