Best way to develop a kapton tape cutter machine?
*Puts on safety goggles*
*Puts on a white lab coat*
*Cracks fingers*
*I am now ready to tackle electronic design questions!*



Instead of using a knife to perform the cutting, use a scissor. A simple servo (the 9g kind) can easily be fixed to one of the scissors blades while controlling the other blade.



It appears I'm not making myself clear enough, so I will show three images that should make everything crystal clear.

This is a scissor:

It's from the Wikipedia link above.

This is a 9g servo:

Reference

Last but not least, a 3D-printer, or whatever method you were going to use to construct your machine. If you have tools for making an adapter, then use your tools. If not, then use a 3D-printer. 

This is how a modern 3D-printer looks like, circa 2018:

Reference

With a 3D-printer, you should be able to make an adapter that fits your scissor and the outer part of the 9g servo. The outer part being the plastic shell with the thin cover on it that says "Tower Pro". I shan't confuse you, the color of the plastic shell is blue. To this blue plastic you can connect an adapter, that you make with a 3D-printer (that I've shown above this text). With the servo (the 9g one) connected to the scissor, you are ready for a second adapter. One that connects the white part (on the 9g servo) that connects to the other blade of the scissor. I'm still talking about the images above. If you do not possess a 3D-printer, then look elsewhere on the Internet for other companies that 3D-print for you. Though, you will have to pay, as if you are a human being. 

This is an electronic design site, where I will give everything and a little bit more when it come to electronics. If you want a 3D-design, then make it yourself or beg someone else.