I have added Arduino controlled stepper motors to my Sieg C1 mini-lathe. Recently I read about the Graphtec Silhouette Portrait cutting machine. I bought one of the Graphtec CB09 cutters and mounted it in the chuck on my lathe (just as a holder, the chuck does not turn) and I was able to cut some 210 GSM card very neatly.
This EBay site has a good picture. I don't want to move my holder at the moment. As far as I can see the spring is just to stop the blade falling out. The holder that the top of the blade fits into is magnetic.
In case you are wondering, the blade rotates to match the direction it is cutting.
There is a lot of info online about the Graphtec cutting machines. All I have done is save myself about £100.