A bidirectional letter opener that fits comfortably in your desk drawer and in your hand like a dice. Use the blade of a utility knife. You don't need to consider the direction of sliding envelope.

I recommend to use the  blade of a utility knife

TI-CRS10 by 3M

Firstly, insert utility knife blade into the narrow slit.

And confirm the tip of the blade stick into the bottom of the wider slit.

Please refer the video how to install blades and use it.

I revised the design to fix the blade fitting into the correct position. And made the distance of the blades smaller than old version to avoid leaving dust after cutting an envelop. 

Changing the distance of blades;

old version

new version

Change the position of blades to widen the cut of narrow slit.

old version

new version

I hope you'll enjoy printing.