This is a combination of walterw's practice tanto combined with cameronlconnor's blank Nerf rail mount. I've found that it fits well on the more modern Nerf rails (Accustrike and Mega), whereas on Elite rails it clicks into place but has a small amount of wobble. Anything from the old n-strike line is a lot more hit and miss, as there didn't seem to be much of a standard to the rails used back then.

The "blade" on this design is quite blunt and unlikely to do much damage, especially if a low infill is used. However, you may want to consider using a flexible filament or cutting a blade shape from foam board if you plan on using this around other people.

Creality

Ender 3 Pro

Yes

Yes

0.2mm

10%

I printed the handle vertically with the blade opening against the print bed to ensure the maximum number of clean surfaces. I used both a raft and supports to make sure it worked first time, though it may be possible to print without either. The blade and tsuba were both printed flat, with supports only on the former.