A slim utility knife holder to carry every day. Press down on the center of the blade and slide to extend.
This is much easier to open one-handed. But https://www.thingiverse.com/thing:3713857 is a more solid feeling design.
Uploaded the .STEP file in case anyone wants to make changes.
Designed to fit the Dewalt Carbide Blades snugly: https://amzn.to/2Xa0Y35
Also fits the classic Stanley 1992 blade: https://amzn.to/2X5oWfT
Right-hand version uploaded. Mirror in your slicer for a left-hand version.
This is meant for light-duty cutting. Opening cardboard boxes, mail, cutting plastic wrap, etc. Use common sense and don't try and use too much pressure when cutting with this.