use a regular Stanley knife blade to insert, this is a first prototype so any other feedback or questions would be greatly appreciated.
edit: V1 is not fully functional, i have made V2 which moves the blade forwards, and the angle of the blade, and also has more of a run to get between the paper. I have not printed this prototype yet, i will do after Christmas sometime, i hope this is a better product for you.
I have also left Version 1 up for people to discover their own solution and to provide feedback.
May include a thinner version for a quicker print, but i like to have something a little more robust especially when dealing with sharp blades.
Enjoy!
edit: major issue fixed, a utility blade should now be inserted without a problem!
The author marked this model as their own original creation.