I like the model of @Archermtl but want to make it in little more “ninja” style.
This one is more as a decorative model but it work too, just be careful to not exerce too much pressure on the handle or it can break.
Work in PLA but PETG, ASA or ABS could be much stronger
Print setting :
0.2 or 0.1 layer height
4 or more perimeters
Minimum 25% infill to have a solid knife but more is better
Print slow the first layer and be sure to have a bed perfectly leveled.
Can use a brim to help adhesion
(If u enjoy my design u can like, follow and tip me)
Disclaimer: this model is not a weapon, and is only intended to be used as a letter opener.
The author remixed this model.
Make in a kunai style