Features

• Small and light weight
• Retractable and safe
• Easy to print and assemble

Hardware and stuff

• 2 x 8x3 mm round magnet
• a Utility blade
• Superglue

Assembly

1. Print the case, the lid, the knife holder, and the thumb slider
2. Glue in the magnets, making sure they attract each other
3. Glue in the thumb slider
4. Put it all together